The problem boils down to what do you image/draw/observe.
If its planets then almost anywhere away from a town is good.
If deep sky then choose the dark area on the Philips dark sky map. In addition, you need to start looking at cloud cover figures – I found some on line a year or so ago (do not recall where). I recall Norfolk way being good and having lower rainfall than most the country, but I’m not sure how it did for fog.
We were surprised how much cloud the Welsh borders got when we lived there. Its within the cloud shadow of the Welsh Mountains. Beautiful place to live, but you can get long runs of no blue sky.
Personally I would rather have a couple of really dark clear nights a month than four mediocre one.