Do the transfer now. It is the only sensible thing to do. You will save long term. If you don't do it now, you won't own the site and you won't own the house. If you don't do it now and your father dies, then you could be in a pretty pickle.
Yes, there will be legal fees - there may or may not be stamp duty and CAT implications. But they just get worser and worser if you don't address them now. Go get proper legal advice on your own particular circumstances.
This is one of the biggest single, most important transactions/commitments you will ever make - could you explain to me why you would not have the property transferred now?
mf