Here's a database on where to find animals for harder letters.

I

Iguana - These are pretty common in reptile collections, Such as the Black Tailed Spiny Iguana is at London Zoo's Reptile House, Greens are at Crocodiles of the World, and Rhinoceros can be seen at Cotswold Wildlife Park.

Ibis - These are pretty common at aviaries - Birdland, Cotswolds, London, Edinburgh are at the top of my head.

 

J

Jaguar - The Jaguar is found at multiple collections, Wingham Wildlife Park, Chester and Colchester. I know Edinburgh once had them, but they left to pay for pandas.

Jird - I remeber seeing that of a single Mongolian animal at Cotswold Wildlife Park.

 

N

Newt - The time my family saw a newt and photographed it was in 2016, Easter Holidays at Crocodiles of the World.

Nile Crocodile - Zootierliste made a mistake with holdings of Nile Crocodile in the UK, saying only Wingham and Noah's Ark housed them.  I also saw feeding time mixed with Morlett's and Niles leaping for a fish.

 

Q

Quail - These are popular in UK collections, Europeans are at Cotswold Farm Park, while others can be seen at Birdland.

Queen Alexandra's Angelfish - Chessington's Aquarium

 

U

Umbrella Cockatoo - I remember seeing one at Birdland, but it has died. They can be seen at Flamingo Land.

Urchin - SEA LIFE aquariums in the UK have lots of them.

 

V

Vulture - Many Falconaries and Zoos have them.

Vicuña - Flamingo Land, London, Edinburgh

 

X

X-Ray Tetra - Chester Zoo

Xenopus - The Jungle Zoo

 

Y

Yak - Whipsnade, Highland.

This is just at the top of my head, I'm sure lots more zoos and aquariums have these animals.