Thanks for the replies. I think the directories will be the way to go. I have managed to put a smile on my elderly relatives face. Blackpool emailed me the employment records for his dad and uncle (my nans brothers), they worked on the trams. He was thrilled to bits.
We have death certificates and marriage certificates but we don't know when they moved there or left. We know they were there in 1921 as my Gt Gran died there and we know they were still in Briercliffe at the end of WW1 because my Nan was in bed recovering from Spanish Flu when her sister came home and asked her to go down to Burnley to celebrate. We also know that my Gt Grandfather and Nans sister had moved from one Blackpool address to another at some point between 1926 and 1935 (a marriage and a death).
The lights and the hustle and bustle of tourists really doesn't appeal to me. If I make a trip, it will be in the depths of winter during bad weather when nobody in their right mind would visit Blackpool