Is there any zoo in the UK that doesn't deserve a mention, as a whole, there is no definatly bad UK zoo, and i'd agree with what previous posters have said. Cotswold wildlife park (my home zoo), whipsnade, marwell, howletts + port lympne, longlete, west midlands, edinburgh (my favorite zoo that i've visited in the UK, and definatly going again next year when giant panda arrive, good collection of ungluates, of course the famous penguin, sun bear, drills, chimps, and the UK's only Koala's - From my experiance, Zochatters think its the 2nd best zoo in the UK after chester, which i've never visited)
hope this helps
hope this helps