I’m looking at the Garmin Edge 800 bundle which comes with whole UK Discoverer maps bundled from Halfords.
They look the same as Landrenger -are they?

I didn’t bother with an OS map card, they aren’t the quality you’d expect from OS maps to be honest. I use maps from the link below, they are based on Open Street Maps which is the Wiki of the map world (from what I remember), I’ve found even the smallest of tracks are on there where as the OS map was lacking a lot and wasn’t as clear to look at.

http://talkytoaster.co.uk/ukmaps.htm

They are the same thing. The Garmin version looks identical to the paper version. When the 800 is connected to your PC you will be able to use the Discoverer maps in Garmin Basecamp too.

OSM is crowd-sourced and so is only as good as the input – quite often being full of holes.

I didn’t like them when I had a look at a friends, missing things I had on my OSM. I’ve not found anything missing yet, but that might depend on the area, some peoples data input might not be as good as others. Get the bundle if the price is right.

Either way, you really need 1:25000 if you actually going to use them for route-finding.

FTFY

1:50k works fine for me