tbh as the fuel all comes out of the same tanks at the same depot there isnt going to be a lot of difference,
for instance, all of the south west area is served by avonmouth fuel depot. shell, bp, morrisons,tesco, texaco. and unless your cars mapped for it they lose power. as proven at many a rr day ive been to, where people are gutted that they've spent ££££'s on engine mods, only to have it all reversed when putting the incorrect fuel in it.
just my 2pence worth