Besides tea and bikes I also have a love of maps. I think the UK must have the best mapping in the world, what with OS, Harvey and BMC all producing high quality mapping. Taking a map to bed rather than a book could be seen as a little strange ... but I'm not alone am I?
Every time you unfold the map and start to pick out the green dashes, black dots, faint yellow lines, etc a picture starts to form in your mind. It's almost like you're already riding this stuff while tucked up in bed ... however it isn't always that simple, it certainly isn't that simple here. A gigantic area combined with a minute population can sometimes lead to the relationship between ground and map not always being what it should.
The picture below was taken at the junction of 2 bridleways, there's even that nice post to lean your bike against telling you so. Your trusty OS also tells you you're at the point where 2 bridleways meet ... on the ground there isn't any sort of track or path, not a mere hint, nothing, nowt!
The second picture shows a very well used track through a forest. An orange marker I picked up close by, tells me that it's been used for some kind of motorsport not so long ago ... but this track doesn't appear on any paper map! I'm sure it'll show up on Google Earth though, so no need to panic.
If you can read a map then finding yourself with your bike lent against the post in the top picture shouldn't really cause you any concern ... just follow the bridleway in the direction the map tells you. The second picture could be a little more tricky, perhaps you've decided that you should take the second fork on the right. You've already passed one junction and you've now reached this one ... be honest, you'd go down it wouldn't you!