Symonds Yat is not too far away, I think (1 hour drive? ) - the west side has a maze, "fairytale land", a funfair type thing and a play area with loads of bouncy castles for (when I was there last summer) £2.50 for all day unlimited entry. It's great and was a real hit with my 2 and assorted other cousins. Also on the east side, I think there's boat trips, too.
We once went to an owl sanctuary which I'm sure was near Kington, they had other animals, too.