i know it's been mentioned before but not for a year or so, so i thought i'd give it a thumbs up. we took dd1 who's nearly 5 and dd2 9m and had a brilliant day. dd1 loved all the birds and there were plenty to see on the walk round. paths very accessible with pushchair and lots of wheelchair access too i noticed.
during school holidays lots of extras: storytelling, water area (for paddling and playing in swimsuits) science-y activities and information about birds and water etc. there is also an inside area for learning opne all year round and tables with craft activities to make badges, fridge magnets, hair bands, etc. the restaurant is also very good and food was yummy.
it cost £17 for 2 adults and 1 child. can highly recommend it. only 5 miles off M5 j13 (i think)