Yesterday I hauled last year's pool from the shed, only to find it had a slow puncture so I've been on the lookout for a new one. I've found this Family Sized Pool with a third off at Wilko, just £10 down from £15 so I'm ordering one now!
This is an inflatable pool with a 1.9m length, so that's more than 6 foot long. You can fill it nice and deep with that 51cm height, and it has a 250l water capacity.
It looks like there's plenty of room for the family to hop in and cool down, and at £10 it's a great price for this size pool.
Click and collect from store is free of charge, or standard delivery costs £4.