We bought our house 5 years ago with 105 years on the lease. We were going to sell up in the next few months, but we are thinking of renting it out now. Mortgage has 20 years left, so the lease will have 80 years when we are thinking of selling - is this really bad? We cannot buy the freehold because of the way the house is (T shaped, walkways under - bridge flat but with 1 room in the base of the T, front door & hall) but it's owned by the council (or it was, and it's been sold in the past few years to a HA type thing), but surely in 100 years you cannot just be booted out? I am worried if we keep it, it's devaluing all the time with the lease. I am kicking myself for buying leasehold.
If you have more than 80 years on the lease then you can automatically (or almost automatically) have it topped up by 90 years. Alternatively, you could try to buy the freehold - there is no "marriage value" (which hikes up the price) if lease is more than 80 years. Contact the Leasehold Valuation Tribunal for more information.
Leasehold is fine (and worth as much as freehold for a long lease). We renewed a flat at 81 years without any problems. As others have said make sure you renew before the 80 year mark. Once it goes under 80 years then you also have to pay a marriage value (i.e the potential profit from extending the lease is split) which makes the renewal far more expensive. I would allow plenty of time as it can be a slow process.