Managed to crack it this week and I've got a consistent roll. Still, at the moment it's 90% effort and about 10% technique. In fact the first time I did it this week I almost cracked my head on the side of the pool when I came out of the water and almost capsized on the other side! Had to put a high brace in to stop the motion.
Quite pleased, It's Good foundation to build upon and hopefully now I can start dialling back the force I apply, as too many of those in the sea will wear me out.