Rather than listing all the procyonid and mustelid taxa within the UK - which would take a while - I will pick out some of the more unusual and nicer species.
The last remaining collection to hold the less-common of the coati species, the
White-nosed Coati (
Nasua narica) is Belfast. They also hold the only
Spotted-necked Otter (
Hydrictis maculicollis) to be currently found within the UK.
There are a few collections which hold the
Kinkajou (
Potos flavus) - however, as a nocturnal species it can be a little tricky to spot. Newquay and Amazon World are the two collections I have had the most success with.
Howletts holds both
Central African Ratel (
Mellivora capensis cottoni) and
South African Ratel (
Mellivora capensis capensis) - neither of which are found anywhere else in the UK. A very attractive species, and very active by mustelid standards.
European Wolverine (
Gulo gulo gulo) are held by three collections in the UK - HWP, Cotswold Wildlife Park and Whipsnade. It is quite active in my experience, although your mileage may differ - I know of one or two people who struggled to see the HWP pair when they were at Edinburgh, despite the fact they were always a surefire spot for me!
Another large and showy mustelid is the
Giant Otter (
Pteronura brasiliensis) which from a position of being almost unseen in European collections a decade or so ago has become quite common, although no less enjoyable to watch. Best places to see them have to be either Chestnut or Chester, both of which have fantastic enclosures for the species.
Whilst we are on the subject of otters, another species which has come out of nowhere in recent years is the
Indochinese smooth-coated otter (
Lutrogale perspicillata perspicillata), which is currently held at, and breeding in, three collections - Colchester, RSCC and Wingham.
RSCC also holds a population of
Northern Yellow-throated Marten (
Martes flavigula aterrima), a species also held at Twycross and Exmoor, although it is currently offshow at the latter collection. Great to watch though.
Finally, Exmoor, South Lakes and Hamerton all hold groups of the very attractive
Tayra (
Eira barbara) - the last of those collections has, in point of fact, bred them a few times. Speaking on a personal level, this is a species I would like to spread out a little more

it is active, looks unusual and is, for all intents and purposes, a slender tropical wolverine!