Most of the food grade pellets you see here are US based. All the usual brands.
Liverpool Wood Pellets supply heating pellets (no, I wouldn't use them) but also used to import Lil Devils at an absolutely bargain (for UK) price. I quite liked them as a general cooking pellet, but for some reason, they stopped doing any kind of cooking pellet a couple of years ago. Obviously not making any money.
A good few years back, I bought some brilliant oak pellets that were made in the UK, for food use. But it was a kind of hobby business, I think, and when I next looked for some more, the guy wasn't there.
Every now and then, someone chirps up that such and such UK heating brand is food safe, but when you look into it, it is "a friend of a friend told me..." and the suppliers themselves say completely the opposite - usually "we are not aware of the regulations for food-use pellets, so we cannot say that our pellets are suitable". I think someone paid a lawyer for that phrase once, and now everyone uses it.
However, I've recently bought from two new local sources, about which I know little, other than the pellets are food grade.
The first company is called Exstream, and they have started selling via Amazon UK. They are based in Somerset, and I can't find anything to say whether they are manufacturing here or importing and rebagging. A full range through - apple, beech, hickory, mesquite, cherry and chestnut, plus more. Their website is non-existant - still showing a default "null" website - but good communications from them.
The other company is Alfresco Chef. Here's an excerpt from their website:
Our Pellets are produced from European fresh cut round wood. The wood is debarked, broken down into wood chips and dried in a rotary drum dryer, before crushing into small pieces and compressing into wood pellets with no binders or fillers added.
Our range of pellets are available in a variety of species to infuse your food with smoke flavour.
Oak
Maple
Apple
Cherry
Chestnut
Walnut (European equivalent to Hickory)
Acacia (European equivalent to Mesquite)
Beech
Interestingly, Alfresco Chef is coming at this not from the pellet grill end of the market, but outdoor pizza ovens, which are increasingly popular over here. See this for their range:
https://thealfrescochef.co.uk/ovens/I've used 10kg of the Exstream chestnut, which was quite nice - not particularly over-flavoured, and I am just breaking into the Alfresco Chef, where I have Apple, Walnut and Cherry, a 10kg bag of each.