I don't know if it's available in the UK, but Mag Phos is great for a pain reliever. https://hylands.com/products/hylands-mag-phos
Genexa is a much cleaner alternative to calpol, you can buy it from Healf online. There’s a kids or infants version x
Cloves are known to be a good natural pain relief. However, I don't know how much is safe for a baby