Cycle Route Website?

Tiggy I think you have to do local searches - or nip into a local push bike shop.

www.sustrans.org.uk/ncn/routes

m.cyclestreets.net

www.opencyclemap.org

Or just Google your town/area + cycle routes

Strava is your friend

They tend to belong to local groups - I know someone who posts ones in Gloucestershire, and a group I'm involved with does ones for south Worcestershire. Our local council has some as well

I like a good old fashioned map, the Goldeneye cycling maps are nice, tend to be by county and show all NCN routes and also traffic free rides.

Cycle streets journey planner is pretty good (but use the website not the app which is very glitchy) and offers you alternate routes depending if you want quiet, balanced or don't mind busy roads. Detailed instructions and tells you what type of roads/paths they are. You just enter a start and end point.

Try the BikeHub app. Doesn't give you circular routes per de but does give you cycle routes if you have a rough idea where you want to go.

I've found Cycle-route.com, strava and goskyride useful.