Extending your lease has been a legal right to qualifying leaseholders since 1993. Leases will continue to get shorter and in some areas of London leases of 40-60 years are common place.
Increasingly legislation has been changing to benefit the leaseholder. For example qualification criteria have been relaxed and it is no longer necessary to live in the flat for 3 years or qualifying periods amounting to 3 years. You will need to own the lease for 2 years to qualify but do not need to live in the flat and can own it through a company. BUT, if you want to sell up, you can sell on your rights under Section 43 of the 1993 Act so the new purchaser does not have to wait 2 years to qualify.
Exercising the right requires a formal legal notice to be served on the Freeholder and all intermediate landlords.
Your statutory right is to an additional 90 years with ground rent reduced to a peppercorn.
Here the Leasehold Guidance Service provides a step-by-step guide to Extending Your Lease.