Simply; you can't.

At most you'll be able to borrow about 3 x your annual income; you'll also need a deposit of at least 5% of the property value. The amount you can borrow depends in part on your credit rating; if you don't have one, you'll get less or potentially no mortgage at all.

You don't get a loan, you get a mortgage - a loan secured on the property. Which means if you don't keep up the repayments, they can repossess the flat and sell it to get their loan back.

A bank or building society is only going to lend you 3 times annual wages, or possibly a bit more, because any more is likely to result in repayments too big for you to afford and still have enough left to live on. If mortgage repayments or rent amount to about a third of your pay after tax, that's about right.

Banks and building societies did lend bigger multiples of pay at one point and got badly burned by it - it's part of what went wrong in 2008, when it became clear that they had lent too much and many borrowers couldn't afford the repayments. That caused a few banks and building societies to go bust (Northern Rock and Bradford & Bingley are two that come to mind), and others got bailed out by the government, so now they've gone back to the good old safe rule of "three times salary". Unfortunately it means that house prices have gone up to being unaffordable. Because people used to be able to get a bigger mortgage, house sellers felt they could charge more just because the money was available, and they did. And now we're stuck with the price of banks being irresponsible.

So realistically the most you will get as a mortgage loan on what you're earning is about half the price of the flat. They won't take any notice of friends who MIGHT move in with you, though if they buy the flat jointly with you, the bank or building society might take account of what they earn as well to give you a bigger mortgage. Which isn't going to help much. The usual rule for a couple buying together is 3 x the first salary plus 1 x the second salary. I don't think this is going to be practical unless your Mum is prepared to bring the price down a long way.

But just for the sake of argument, let's say this IS possible - maybe you inherit enough for a much bigger deposit. Maybe you know some of the rest already but I don't know that so it's best if I say everything.

You have other costs to consider. You will need a solicitor to handle the legal bit of the purchase. Even if you don't want searches done because you know this flat and the local area so a search with the local council will tell you nothing you don't already know, you still need one to handle the contract, exchanging of contracts, and the Land Registry paperwork to get yourself registered as the new owner. (I've actually done this without a solicitor, and legally you can, but I had to read up a lot first to know what I'm doing, and I still had the Land Registry fees to pay.) Quite often a solicitor will charge a flat fee to do it but you're still looking at another thousand pounds or so to cover their fee, Land Registry fees and whatever else they need to pay out for you.

Fortunately £80,000 isn't enough to have to pay stamp duty (a tax on house sales).

And do you want the flat surveyed to make sure it's sound and won't fall down tomorrow? Even if you don't, your mortgage lender will send a surveyor round to value the flat and say whether it's worth at least the amount of the mortgage loan. If it isn't worth that much, you don't get a mortgage. And you have to pay for this, and the cost of the lender's solicitor to draw up the mortgage deed.

The mortgage lender's surveyor will not do much - all he or she does is provide a valuation. It's not a proper survey, and too many people don't understand this. I know because I've seen it in my own flat. I remortgaged the flat because I could get a better deal with another bank, and the new bank sent a surveyor round because it wants its own assurance that it's worth at least what I was asking for to pay off the previous mortgage. So as I already owned the flat, I was there when he came round to do it! He looked round for 5-10 minutes and left. He didn't prod walls, want carpets taken up so he can look at the floorboards, that kind of thing... if you get a full structural survey, the surveyor WILL do that and take a lot longer over it.

So here's a tip for future reference: if you want to buy a property and you want it surveyed, get the bank or building society's surveyor to do it. Then they can do the home buyer's report or full structural survey at the same time as the valuation, and it's cheaper to have just one surveyor do the whole lot in one go :)

There is more to pay for up front than just the deposit. It's not like buying anything else.

Is the flat freehold or leasehold? Banks and building societies hate freehold flats and it's almost impossible to get a mortgage on one.

The point is that you aren't fully responsible when the flat is only part of another building. You could be affected by what happens in other parts of the building. And what land do you actually own (because the law on this is all about land ownership) when you're like me and your flat is on the first floor? I live in a converted office block with 94 flats in it, there are 4 floors above me, and under me are some of the parking spaces - if my flat was freehold, it'd be a "flying freehold"! Freehold works for houses because then clearly what you own is everything from the ground to the sky, and you're totally responsible for anything within your boundaries, but for flats... well, it's not that simple.

So it's done the only practical way - there's a property management company that owns the freehold, they look after the common parts such as corridors, stairs and lifts, I pay a service charge for them to do that, that includes insuring the building, and what I actually bought is a lease that allows me to live there for 999 years. (There is also such a thing as commonhold where all the flat owners own part of the freehold between them but this really hasn't taken off - for us, all 94 flat owners would have to agree to convert to commonhold. Nah, we're not going to... we'd still want a management company to do what it does now, so it would only make life more complicated to change it.)

Even if it's a just a house with two floors so two flats, one on each floor, let's say you have the downstairs one - you're still relying on whoever lives upstairs to keep the roof in good nick. Same problem.

I mentioned a period of years - that's another thing with leasehold properties. How long does the lease have left to run? Unlike freehold, you aren't buying the place outright, only the right to have it for as long as the lease lasts. I bought a 999 year lease 17 years ago, so it has 982 years left to run, and nobody will have a problem with that if I move now. But if the lease has less than about 75 years to run, and you intend to live there for some time, who will want to buy your flat with only a few years left on the lease? You certainly wouldn't get back what you paid for it.

So there's a lot to think about! If you still think you want to buy this flat, your next step would be to make an appointment with your bank or building society of choice to discuss a mortgage and how much they would be prepared to lend you.

You don't earn enough to get the money, so unless you have £40K tucked away as a deposit or your mother is prepared to sell it for 50% of that £80k then you will not be purchasing it

Go talk to an advisor at your bank or building society.