http://www.countrysideinfo.co.uk/rhododen.htm

Wow. Very interesting.

My first thought is that you apparently have soil which is good for
plants of the heath family (cranberry, bilberry, heath, lingonberry
aka cowberry, etc), so you could try a few of those.

I'm jealous. My soil is not acidic enough, so we try to amend it.
Not sure how long we'll keep up trying, and when we'll give up.