Good Bike shops I’ve used before, and wouldn’t hesitate to use again (in no particular order):
Cheltenham Cycles
Worcester Cycle Centre
About Bikes near Evesham
Sideways Cycles (yup, Tim is as good as his reputation!)
Swinnertons Cycles
John Atkins Cycles
Coventry Cycle Centre
Bike Shed in Cardiff (only been there once but they gave me massive discount just cos they know my mate!)
Beeline Bikes in Oxford
Noahs Ark
JE James in Sheffield
Any of these I would happily use again in their vicinity. There have been plenty of bad bike shops I’ve visited in the past though, and without wishing to name names, usually the larger the bike chain or the store, the worse the service is. You may not get the range of products in a smaller store, but more often than not (in my experience at least) you get much more helpful/knowledgable staff and a better service, and the possibility of discounts too (often without even asking).