How rural are we talking here? If you're looking for something very rural and very quiet you can't really beat Pembrokeshire imo. Lots of beautiful rural walks and great night skies there if you're into that. The only problem is the logistics if you don't have transportation because you're not going to be able to just hop on a bus or walk to the shops. You really need a bike or a car to make the most of it.
A nice middle ground might be somewhere like Glastonbury, or if you prefer seaside towns, Lyme Regis.
Glastonbury tour is beautiful to climb all year round and you have lots of little quirky English shops and pubs around. You also have Street just around the corner which has a shopping village with it's own selection of pubs, shops and restaurants.
Lyme Regis is just a beautiful quiet seaside town with lots of history. It's a little touristy there, but not like other English seaside towns - it's appeals much more to retirees and people looking for a quiet break than a family holiday.
Would love to host, but my place isn't really appropriate. Happy to answer any questions though.