would like to do say a coast to coast ride and see the route as I progress on screen via a smart tv or similar
Almost, but not quite.
BigringVR and the TACX trainer apps (and others) have films of routes so you can see moving pictures of the route as you ride along. Also trainer resistance is synchronised with the road gradient so you get the hills. But the number of routes is limited to places that have been visited with a camera, and painstaking techy stuff done so the film can be synchronised with your ride. So there are only selected routes available. Not just any old route. They tend to be famous climbs and stuff like that. You can interact with other riders doing the same route to a limited extent, but not as much as RGT and Zwift.
TACX has a facility where you can follow the route of a GPX file you upload on a map on screen. Others probably have this. You can watch your dot proceed along the map and you get simulated hills, but no pictures.
RGT has realistic virtual simulations of famous rides. These are like the Big ring VR and TACX films except they aren't films, they are a virtual world. You get to interact with the avatars of other riders in this virtual world. You see the countryside pass by and resistance is synched with hills. But only a few special routes (famous cols etc) have been done because of the effort it takes to prepare a virtual route.
RGT also has a thing called "Magic Roads" where you can upload a GPX and ride it and get the simulated hills (like you can with TACX). But the on screen scenery is all made up. It's a bit weird.
Zwift is like RGT in that it's a virtual world, and you can interact with other riders, but it is a fantasy virtual world, unlike RGT which is a replication of real world climbs etc. So you can't simulate riding in real places on Zwift, unless they go to the effort of including that place in their fantasy world.
But there isn't (as far as I know) a service where you can pick an arbitrary route (like coast to cost) and it will simulate the hills, and also give you pictures of your virtual location.
Some of the above is probably wrong, but hopefully the gist is right. Apols if I missed out anyone's favourite service above. The ones I mentioned are ones I looked into last year.