Thanks for all the recommendations!
We went with Cindys Swim School and they've been great! Small classes and good locations and you don't have to get in, bonus!
The also do holiday crash courses so we're going to book one for Easter (for my elder one, I'm not a pushy mum of a 3 month old
)
They offer a referral discount so if you fancy 10% off PM me and I can send you the code.
Thanks NVN!