You won’t want to hear this but there is not enough due diligence in the world when it comes to buying leasehold.
I bought a really nice flat 3 years ago.The property was sound, met all criteria regarding lease terms, ground rent, service charges, etc. I spent hundreds of pounds on a full survey of the whole development to flag up future maintenance issues, and general condition. The report came back clear, with no looming major issues. I did it all, including acquiring historical accounts, door knocking to hear (prospective) neighbours opinions and experiences of the managing agent. All good. I went ahead.
Within 1 month, a new managing agent took over. Totally incompetent to the point of unscrupulous. The new MA commissioned a survey (at the leaseholders’ expense) and announced, without warning that we, the 22 leaseholders, faced £550,000 of repairs over 4 years. FFS! Their motive was the 25% fee they would add to the total for “managing” the work.
A huge, stressful fight ensued, with me, the newbie, as the organiser and ringleader of a leaseholder rebellion. The MA backed off but is now refusing to do anything other than grass-cutting and window cleaning in future, citing reinterpretation of the 60 year old lease.
I cannot stress how terrible this was for me and the other leaseholders. It’s still not resolved and as a result the flats are currently unmortgageable, therefore unsellable because the MA’s refusal to do anything regarding maintenance & repairs to individual flats and communal roofs. A Tribunal is the only way to resolve this and that’s going to take a year or more.
If you can do anything to avoid leasehold, avoid it. Or, wait until the leasehold reform is implemented which may (or may not) improve the rights of leaseholders. Good luck.