The landscape in the different areas is as a result of thousands of years of changing climate. The most significant period that resulted in the current landscape was the last ice age where most of the area now known as Britain was covered in a huge ice sheet. As the ice sheet moved across the United Kingdom it cut great swathes through the landscape. These changes were then further developed as the receding melt water flooded down the newly cut glacial valleys cutting rivers, gorges and valleys. Big piles of rock that had been caught up in the ice sheet were also dropped back onto the landscape creating moraines which are a regular feature of the current British Landscape.
The UK has been exceptionally well mapped and various scales of map are available and cover the whole of the UK. The National Parks in particular are extremely well mapped. It is always advisable to carry a good local map when you go walking and a compass, whistle and waterproof jacket (British weather is famously changeable).
Footpaths are generally well signposted but in some more remote areas this may not be the case. For the best sign posted routes it is best to stick to the large national routes that are maintained by national government.