Today i phone and basically get told that the 1st and 2nd people were wrong and although fibre is active in my area BT haven't given Sky access to it yet
I don't believe that "BT haven't given Sky access". Sky work differently to most ISPs in the way they take fibre services and have to themselves do work at the exchange - I suspect they haven't done that yet.
Also fibre checkers since Sky talk went active have changed from 50-70mb for fibre estimates to
Estimates are estimates - no matter when you sign up it is irrelevant as they fluctuate as do line speeds. It is possible that a number of people have signed up and that the cross talk has increased. Even if you signed up when the estimate was higher you would still only have got whatever your line was capable of.
Sky should have told you when you first spoke to them that they hadn't yet done their bit at the exchange. If you want to go back to BT then I would ring Sky, tell them you are going to migrate
within the cooling off period and then contact BT to get the ball rolling. I would also contact Sky via a written medium just to confirm to ensure they can't then say that you hadn't told them.