Is it the Sheerness Swimming Pool?
It looks like the place we went to in Sheerness once as kids. The water was freezing. My Dad decided to try the top diving board but when he got up there it was higher than he expected. He tried to come down but there was a queue coming up behind him so he had to dive. He didn't enjoy it at all as he hit the water badly.
If it's not there then I need to search further...