These are the most popular maps for walkers in the UK. They cover the whole country and are known as Explorer maps. The more popular walking areas are available in laminated waterproof versions that you can write on and wipe off (or clean off with meths if you use permenant marker)

These maps show areas of access land where you have the 'right to roam' as well as all the different sorts of footpaths and bridal ways.

The contours are usually at 10m intervals but in some areas (flatter area's maybe) they are at 5m intervals so make sure you check.

These maps have a lot of detail so are ideal to learn with as there are plenty of tick features to choose from.

You can buy OS maps from here.