Are you looking for the first Divinity game, or a UK version of Divinity 2?
page lists a few UK online sites (as well as other regions) for D2:ED orders, but I don't know how many would have the original Divine Divinity (Amazon does, and there should be a few UK sellers with it on eBay, as well).
A remastered version of DD is available for download from GOG
, which would be less expensive than a physical copy.
There are no PAL version computer games; PAL / NTSC only matters for TV / VCR / DVD video. UK and North American computer games are interchangeable. I don't know why some retailers list PAL format in game specs, unless they also sell DVDs, etc, and it is easier to leave that in than change the forms for computer games, or they are just using PAL to mean UK version.
Welcome to the forum.