Another thing to consider with Blackpool might be the traffic to and from the field. In my experience the M55 is a bloody nightmare at this time of the year , especially if you were looking at doing lessons over the weekends. Ever considered Liverpool? It has easy motorway access to the door, and 3 schools to choose from: LFS, CATS and Ravenair, I don't know the costs but if you are going to be spending £4-5k they might be worth looking at for the price of a phone call.
T.