Power supply has been ordered.
Thanks to a bit of advice from MetalMan1 i have ordered these, http://www.ebay.co.uk/itm/1112970984...84.m1436.l2649 For the sake of just under £8 GBP i ordered 10 just in case i manage to blow up a few. I have also ordered some heatsinks separately just in case. If they do all give up i havent wasted much money and will order a DCDC-USB-100 or 200 instead. Adding a fan to the heatsinks may also be an option but we shall see.
My electrical knowledge isnt too good so if anyone could tell/show me how to wire a couple of these in parallel that would be great