Thanks for all the replies

we went yesterday and had a fantastic day!
I am not very good at reporting but will just say what we enjoyed and what we felt was not as good as expected!
We arrived at the car park at 9.30 just as it was opening so we were banging down the door to get in at 10.
Straight into Gorilla Kingdom which we both thought was fantastic! Lovely viewing area and the gorillas were all very active first thing. Would have loved to see them climbing. Very impressed.
Next we went in the African Bird Safari another plus!! Even though I have a fear of free flying/roaming birds I enjoyed it (even though they all had beady eyes *shiver*). Then the reptile house! What an amazing collection, really blew us away! Fantastic building and we really didnt spend long enough in there but there was to much to see.
Next the Mappin terrace, not a lot going on took more photos of baby ducklings, but interesting to see from the photo in the gallery how it once housed polar bears!
Komodo Dragons HUGE disappointment the exhibit was closed due to maintenance??! Was looking forward to comparing them to Colchester's!
The Aquarium very interesting collection, again we could have spent longer. My partner was disappointed it wasnt bigger.
Next into Africa, Hunting dogs asleep on 1st circuit, second time round all awake and running up and down hunting a dog on the other side of the canal! another highlight!
Warthogs were getting upset by 2 keepers lowering a water trough into the enclosure and the male was putting on a wonderful show of snorting and pawing the dirt, very threatening!
The other animals were all browsing but the tapirs unfortunately were asleep!
It was a very warm day!
Snowdon aviary, again fantastic (conquering that phobia) the structure alone is amazing and i took agood few photos of that alone! Didnt do the rest of the birds we were hoping to go back but was to tired!
Clore Rainforest was brilliant, the sloths were very active even the keepers were surpised! Only disappointment I didnt see the jumping rats at all and its a shame the bats aren't in a walk through exhibit, good ground views of the rainforest.
MeerKats - a baby was out so very crowded, otters all asleep, impressed with there enclosure and the heron fishing in it.
Lunch on the picnic lawn - a welcome break.
Pengiun pool very disappointing seemed to be more of an advertising space for the sponsor ppppp pick a more inspiring design or maybe its just that whipsnade's comes with a stunning view.
Through the butterfly paradise, the pelicans and flamingos were very photogenic in the sun.
Into bugs another fantastic building and again we could have spent alot longer reading all the information available and studying the bugs etc at length. No anteater in sight.
Meet the monkeys - only a couple we could spot but a very busy exhibit.
Blackburn Pavillon - another highlight and impressive building! slightly freaked out by the hummingbirds getting a bit to close.
Lions and tigers both asleep as per

Old penguin pool - another highlight and a fantastic use of this amazing piece of art deco/modernism at its best. took plenty of pictures.
Animal adventure - unfortunately it was packed and we didnt go in.
Camels - think they could have made more of this enclosure given its previous use.
Pygmy hippo pool was empty.
And back to the gorillas again
We went round a few more for a second look!
Overall a fantastic day but both felt we have been now and would probably not use our membership of ZSL to come again but would definately use it a lot at Whipsnade this year!
More of an issue with the location than the zoo its self, there was plenty of quiet corners and according to the staff it was a quiet day due to the marathon!!!
Well worth a visit tho and although we felt we had seen most things we wanted to we could have spent longer at some of the exhibits as there was so much to see.
Sorry my review isn't up to much, and thank you for all your advice, it was a great help!