So I'm in the same boat, was working in the US where the availability of products was easier. I should have just stocked up on some bars before returning to the UK but alas.
I do love Dr.Bronners for my body (though the peppermint does dry my skin a lot) but I don't use it for my hair.
Now I'm trying to look at the options available in the UK and I've come across This from www.dreadsuk.com. The site its self doesn't give me huge confidence but if what it says is true the bar looks ok.