Most UK houses are freehold. Most UK flats are leasehold — practically necessary because flats share land + structure with neighbours. A few flats are "share of freehold" (you co-own the freehold of the whole building via a freehold company with the other flat-owners) — generally the gold-standard tenure for flats.
Leases under 80 years are problematic: marriage value kicks in on extension; mortgage availability tightens. A lease under 60 years often needs immediate extension to remain marketable. Pre-purchase due diligence always includes the lease term + any restrictive covenants.
The Leasehold and Freehold Reform Act 2024 (passed but not all sections in force) gives leaseholders new statutory rights including longer extensions (990 years), simplified enfranchisement, and a process to commute ground rent to peppercorn.