https://cycle.travel/map
Completely free. All features including downloading the trip onto your gps/phone, gradient profiles, saving of routes etc are free also. It has direct links to google streetview if you want a better look at the road. There is a patreon page which I pay into at a cost of about £3 or £4 a month for which I get access to official OS mapping and satelite views plus some other stuff that I can't remember atm.
It's brilliant. Better than that RWGPS crap. I gave up that years ago when they started adding charges for this, that and everything else. I still use it for logging my rides though.