It depends what standard you are planning on doing it to, but my refurb is being done to an OK standard, a bit up from basic, but not much and the prices you have estimated are about the same as for our small 3 bed terraced house/single garage build.
Managed to do my large 3 bed terraced for around £30k 10 years ago but did a lot of labour myself. Included roof, plastering, complete central heating system, electrics.
