Thanks so much for the replies. All very helpful - I will definitely join the Leaseholders Association. I've just had quite a helpful conversation with someone at Southwark Council, who has said that they haven't inspected my property yet so can't say exactly what will be needed. But they confirmed electrical/boiler/insulation works won't apply to me as a leaseholder. He said that they will check the windows, roof etc to see if there is a problem but if the condition is ok then I won't have to pay anything, although if they do decide to replace the windows the cost will be ?3-4000 plus fees etc. And he also said it's unlikely there will be any other major works within a 10 year period. So that's put my mind at rest somewhat... although of course it's still a risk because if they do, for instance, find a problem in the roof I could be stung. Also, interestingly, I found out there's only two leaseholdes in my block which makes me think I might try and buy the actual freehold in the future.