I mean, I picked up some good authentics from those acutal shops in UK, vape emporium and grey haze. But almost all of the shops I have access to in North Yorkshire sell only clones.
Many clones are excellent quality. Some are garbage. If the shop knows the manufacturer of the clone, you can probably find reviews online of that clone. If not, you should ask to look at it. Verify that there is no issue with the threading, the posts, the screws, the o-rings, etc. If everything fits together correctly, its probably going to work well.