Lots of brands on sale in the UK, and have been for many years. Back in the 1950s there was even a hugely unprofitable government
"Groundnut Scheme" to grow peanuts in Tanganyika, which lost millions of pounds, though the idea there was mainly to get vegetable oils. I don't currently have a jar in the house, but I do intermittently buy the stuff - it's good comfort food. I usually have it with a little Marmite (savoury yeast extract similar to Vegemite), but I've eaten it with jam, or on its own. I think that most of the peanuts used to make it in the UK come from India and China, but I could be wrong on that.
later Wikipedia says China exports peanut butter as well as the nuts, I'd guess that a lot of the product on sale in the UK is made in China.
Maybe I should add that products made with peanut butter (e.g. sweets) don't seem to be made in the UK - Reece's cups and their other peanut / chocolate products are around, but are imported from the USA and fairly pricey.
