Meindl do a comfort fit range that are built on a wider last than there usual boot. They are worth a look at.
Louis
Yeah, Meindl are worth looking at, but finding a store/shop that holds appropriately sized stock is difficult, most places stocking the popular sizes only. A good shop however should be able to measure your feet and order in suitably sized boots for you to try.
Generally I find the fit/sizing of most outdoor boots to be on the small side when compared to "normal" shoe fit sizes.
I'm a UK 12 in my left foot, 11.5 in my right, but I struggle with UK size 12 boot sizes even though their meant to be sized to take a thick sock.
I recently bought a pair of hanwag approach shoes and was pleasantly surprised at the fit of the 12's, and ended up leaving the shop with an UK 11.5 that fitted my feet perfectly. They do a UK 13 which may well be on the large size, with room for growth.