Any reason you can't use a map
OS map, compass. Cheap, needs no batteries - bugger in the wind and rain though!
Can also make colour copies of the bits of map you need and use that. It's what I do on longer trips, can fold/ shove the copies wherever, up your sleeve etc.
Not as convenient as a Satnav/GPS, but cheapo and workable.
Maps have the added advantage that they give a better appreciation of the terrain and the layout of the area.
I know it's not the answer to your question, but it's an alternative view!