I can recommend these National Trust walks - click the link to see them. The Trust owns some of the most beautiful scenery in Britain. You can also stay in some of their bunk houses, which are rather like youth hostels used to be, only a bit more comfortable - and without those tedious chores!
Here's one of my own pictures taken in a very unusual National Trust property in Orford Ness, Suffolk. This was a weapons testing facility for many years and has an eerie, otherworldly and not entirely pleasant atmosphere.
There's also a nuclear bomb on the island - decommissioned, hopefully.
Naturally, most of the other National Trust walks are much prettier and less, shall we say, quirky.