I think R&R Music in surrey will do it for you if you want. Just explain what you want them to do.
It's pretty easy to do yourself though. Get one of those mic jacks with the metal plates, find a drill bit that is the size of that jack (or a bit smaller then you can just make the hole bigger yourself), drill the hole, put the mic jack through the hole, screw small mic stand to the inside of the dho, splice the mic wire and solder it to the mic jack and you should be good to go.