It could be more than £150k if your freeholder hires a connected company to do the works and inflates the bill all over the place. Although maybe you are share of freehold so avoid these problems.
Started saving. Once they serve the Section 20 (IIRC) notices there is precious little you can do as a leaseholder to halt the process without getting dragged to court, with the requirement to pay their legal costs when you lose.
It could be more than £150k if your freeholder hires a connected company to do the works and inflates the bill all over the place. Although maybe you are share of freehold so avoid these problems.
Ask me how I know...