Have you had a survey? We bought similar but found a lot more that needed doing - new windows, repointing, new roof, wiring a bit of a mess (some needed redoing and chasing in), new doors upstairs etc. It adds up.
Adding an upstairs bathroom was pricey as we had to have a chimney breast out (as we stole a bit of a room). FIL fitted the suite and ran the pipes for us, except the soil pipe which was done by the builder who did the chimney. Electrician to do lighting, and put in an inline extractor fan. All in with tiling, suite etc, adding a 9x4.5ft shower room came to around £12k.
Kitchen - you could spend loads or not depending on brand and how much you can do yourself. Ours needs rewiring and the subfloor is a mess - half boards, half lumpy concrete - so we can't just lay flooring, which adds £.
Replacing a boiler isn't too bad - moving it or putting in a whole new system, on the other hand...
Decorating yourself is a good money saver but be realistic about the amount of prep. Our bedroom was a mess due to leaking roof, pockmarked plaster, cracked ceiling etc, took about 6 weekends of prep. In hindsight I should have had it skimmed rather than spending so much time filling and lining it.
If you don't need any new furniture out of that, can source things like bathroom suite yourself and look for bargains, & you are happy with a budget kitchen, I'd say it's doable. But be prepared for it to take ages
it always takes way longer than I think!