As above, ride with gps is giving you “advance turn notification” in a TCX file, which is not quite the same as proper turn-by-turn. Garmin 800 can do proper turn-by-turn if it has the right maps (see https://ridewithgps.com/help/export-file-formats#turnnotifications)
I use routable openstreetmap maps, which you can get from http://garmin.openstreetmap.nl/
My Garmin came with the OS maps, and I thought that they were routable, but it’s years since I’ve used them. I prefer the OSM maps as they’re vector maps so you can zoom in further, whereas the OS 1:50 are bitmap maps, so just get blurrier as you zoom in.
Once you get the right map installed and enabled, I find that the turn-by-turn works really well, at least on road. It’s really quite brilliant to be able to plan a long route taking in all the fiddly little unsigned back roads in an area that you don’t know and just head and ride it without stopping to look at a map at every junction.