I have seen a couple of postings by you regarding nice B and B's in different parts of the country. Have you come across the website www.sawdays.co.uk
You can search by county/area/town and it has some beautiful places to stay that would seem to fit your requirements. Have to admit they are not the cheapest you can find- but they certainly are special. They even have a 'garden-lovers' section. I've used the site several times now (including finding a couple of overnight stays in France where I wanted to stay in a B and B Chateau!) . Even if you don't find anything suitable it's nice looking at all the beautiful properties and their websites.
Hope this helps.