Not strictly a day out, but just wanted to tell you all that Shweppes have been doing a free swim promo for a while now. You buy either a 500ml or 750ml bottle of their Abbey Well water and keep the cap once drunk. Then you look on their website to find your nearest pool and free sessions in the promotion and go there with your caps for a free swim.
I've done this all summer with my DCs, at the pool nearest me, I pay only for me and my 7 year old DD, my toddler is free anyway. It saves me £4.20 each time. Last week the session we went to was a family fun one with inflatables etc.
Morrisons are doing two 500ml bottles of the water for £1.00 at the moment.