My Mum has lived in her house for 60 years...It appears that it is leasehold?

I'm afraid your mother is about to lose her house. Big mistake in not renewing her lease, what was she thinking. Would have cost her little more to renew the lease and buy the freehold at the same time whilst it had over 70 years left and would have been just a couple of thousand pounds. Now the marriage value (cost of freehold) or extending the lease to 99 years will cost almost as much as buying the place from scratch so I'm not surprised she cannot afford it.

What will happen at the end of 12 years is that the house will revert to the freeholder and she will need to pay a market rent to stay on. If she pays, she cannot be evicted as it will be an assured tenancy but if she cannot afford to extend, she is unlikely to be able to afford the rent either.

Most leasehold properties have automatic renewal clauses and elevator clauses that limit how much the ground rent can increase.

Your solicitor reviewing the lease is going to be the only factual answer you get.

You may be fine; you may be moving in 12 years; your rent may increase by 100 fold.

For the most part, each lease is different with different terms.

She can either buy it out, save up and buy it out at a later date, or wait for the thing to run out and see what happens. I kinda think she'll be allowed to rent it when it runs out but who knows.

There is a huge apartment building kinda near me in a sorta similiar position. 99 year lease that runs out in 10 years. However these units are owned by people until the thing runs out in just 10 years. So there are people trying to sell their units but any buyer knows they'll only have the thing for 10 years so what are you willing to pay not to buy a unit but to get 10 years of use in a unit (and what bank would lend on that). Prices of the units are way below others in the area but for this excellent reason and everyone is scrambling trying to figure out what to do next.

You may get a good enough answer if you take this to your local CAB, but to be sure, I'd be finding a lawyer who specialises in property law to run through the Title documents to see exactly what is the situation. And do it soon!!

ps The Freehold may not be available - and you need to find out about this too. You/she may yet qualify for a mortgage?

I think a solicitor would be your best option. There is some information on the link, but so many things depend on something else, so on paper, it looks complicated.