What would you budget for the following works?

suebfg

I'm in the process of buying a house and am concerned that I have underestimated the cost of the works required. I have budgeted £70k including VAT and contingency, cost of new kitchen, bathrooms, flooring and tiling - I'm in the North if that helps. Kitchen/bathrooms to be mid range quality.

I need to buy in the labour - I won't be doing any of the work myself.

The works are:

Single storey side extension of approx 20 ft x 10 ft to enlarge existing kitchen diner with Velux windows and French doors
Rip out existing kitchen and install a new one
Creation of utility room within extension
Creation of study in existing house (partition wall, door etc)
Rip out three bathrooms (one downstairs WC, one main bathroom, one ensuite) and install new bathrooms

What do you think?