Only you can decide, but for what it’s worth I would say yes and move forward. The process is never fun, almost always painful, and if it makes you feel any better about it the hoops and tribulations you have had to dance through are probably on the lighter side of the hassle curve in UK property transactions.
The boiler issue isn’t really here nor there in the grand scheme of things (though it’s nice if it’s been done). The ‘major works’ issue is just part and parcel of buying leasehold, especially where an organisation (as separate from an individual) is the freeholder. I think you said that no works have actually been planned, they’re just assessing at some point in the future if something will be required. This is effectively the case wherever you buy, even freehold - at some point in the future some money may need to be spent on maintenance. Will need to be, ultimately, in fact.
If you like the place, and the block, and the location, and would like to be living there, then don’t let the pain and perversity of this process put you off.
Just my opinion of course. But if you do go forward soon all this will be in the past and fading and you’ll be in your new place happily domesticating it.