We are not in the UK. When we got our first cat way back in the mid 2000s, we tried to adopt three times and:
a) The first cat was lovely, but after a few days the shelter contacted us and told us that the owner had decided to reclaim him after giving him up (!). Apparently we should have been sending photos and messages to the shelter for the shelter to forward to her to reassure her that her pet was now in a good home. We had to give him up.
b) Second try: we were sent to a private home, which was full of Russian Blue cats. One young cat was terrified of people and hid immediately. Very very scared cat. We were told that this was the one that was going for free. Clearly a breeder who had decided to offload one animal for free as nobody would be prepared to pay for it.
c) We were matched with an animal which on the first day home bit me so deeply I got a massive infected puncture wound and had to have it drained at the hospital. I grew up with cats and know how to handle them gently and did absolutely nothing to startle the animal - it was an aggressive, unprovoked attack. The cat showed weird behavioral tendencies which suggested it had been dumped for being unsuitable as a pet. We called the shelter and asked them to take the cat back.
My husband said we were giving up on rescues and insisted on getting a kitten.
After our cat passed on from old age last year, we looked into rescues again and this time, with the internet being so much more developed, we could get recommendations on good shelters. We were matched with two kittens who are now lovely cats.
I would always recommend rescue over buying a kitten now, but would also like to point out that dodgy shelters sometimes need to take some responsibility for adopting being less popular.
Some shelters have requirements that are truly ridiculous - we have all heard the stories about this.
Other shelters seem determined to "save" every last bloody animal due to sentimentality or obsessional behavior, and as a result they end up pushing or nagging people to take animals that are not what that family wants or are dangerous or full of behavioral/medical issues.
It would be better if shelters could be a bit more practical and hard-headed about this kind of stuff; have high-enough but SENSIBLE standards, and be aware that the world is full of decent, unwanted animal and euthanize those that are not likely to find willing owners for the above reasons (including huge numbers of unwanted pitbull types dogs etc.), and then focus their resources on showcasing and providing homes for a smaller number of animals that are likely to be excellent and wanted pets. If shelters could make sure that virtually every story of shelter adoption was a positive one, we could make some progress in getting people to "adopt not shop." Well-intentioned policies like keeping borderline animals alive and nagging people to take them anyway, result in bad stories which really put people off.