Expect to do more than you think.
We have just bought our 1st house, thought it was just going to need to be redecorated and then move in.
Turned out we needed a full rewire (2.5k), which then lead to the whole house needing plastering (2.9k), then decided we should replace the fire place for something more modern (3k) then flooring for the whole house (3k). we made the stupid decision to decorate ourselves, Biggest mistake we made. If I did this again I would get someone in to paint. Had to sand down all the woodwork which was a horrible dusty job. All this whilst working 12 hour days like most of us.
Had the house 3 months now and not spent a single night in it yet. Can finally see the light at the end of the tunnel but it's been stressful at times.
Also if you can, do as ekona says and run data cable. I have run cat 6 around the house which is a bit over kill at present but I thought I would future proof, and now get 72mbs out of the wall in every room. Actually enjoyed wiring everything. If you want to see some pics of the transformation have a look at my Instagram jimboy2