Hi there,
Not sure whereabouts in the NE you're from but have you tried 'Waves' at Whitley Bay? The pool is never colder than 29 degrees ( the temp is displayed on a big screen by the pool) and the changing rooms are fairly clean. They have quite a few family changing cubicles too. It's only been open a few months, so it's quite modern.
It can be a bit busy at the weekends, but it's good fun. The bigger pool has waves every now and again which can be a bit much for the littlies, but the baby pool is good, and has a pirate ship with slides etc although not sure how old your baby is, this might be a bit big for him/her
Hope this helps
Jen x