The average price I've seen quoted for a loft refurb on MN in the last two months is 65-85k. If your refurb budget is 150k, I don't think you're going to get the rest of the house done for 85k.
It was only added 10 days ago, and almost no-one is buying doer uppers at the moment. I bet if you wait for the 1 month mark, you'll see the asking price have a hefty reduction.