Hi Dave
You might want to try phoning your chemist first for the Morton's Epsom Salt Lotion. Another poster said they had tried to buy it around the UK and it wasn't available (same in NZ). MrsD gave them info on another brand. Here's the thread:
http://neurotalk.psychcentral.com/thread195462.html

Also there's a recipe for DIY make your own.

I tried a quick search in the iherb online catalogue but couldn't find it listed but there are other sites, eg: amazon & walgrens, that do stock it.
Good luck