Please help frustrated as hell trying to work out how to plan routes and download existing routes lots of research suggests delete the existing maps and down load new non garmin maps?!?! Bit nervous doing this

Don’t use mine for offroad routing but for on-road I use RidewithGPS to plan and save routes, exporting as GPX Track. Works fine like that.

For the mapping changes, you can always backup everything from the device itself to your computer before deleting, and restore it if you have any problems. From memory the unit itself allows you to specify which maps it uses, without you necessarily having to delete the others.

I use the Garmin maps just fine. Main thing is how you plan your route and for that I like bike route toaster. Spend plenty of time getting the turn warnings right and following the route is nice and easy.