I'm not sure about where in Britain you can find supplies; I'd recommend using Google and searching for reptile supplies with your hometown name or area as part of the search. Probably the most efficient way of finding them.
I don't know if the theory's still the same from back when I got Fantus, but I was told that getting a small tank first would actually be helpful for the baby beardie. They do grow out of them quickly, so a basic 10 gal. aquarium with the proper accessories is a good starting size. Fantus went from 10 to 29 to 40 in about a year. He seems very happy with that size, although I keep thinking he'd be better off in something larger (although where I'd put it I have no idea).
You will need a source of ultraviolet light, a heat source (infrared lamp), a rock for him to climb on and hide under, something to line the bottom of the tank (for babies, paper toweling works just fine). You'll need a food dish and a water dish, and a reliable source of the food you choose to give him.
Fantus grew up on silkworms, which are pricey and, unfortunately for me, something I found out that I'm highly allergic to (actually, I probably *developed* the allergy in handling them for him). Ryath grew up on mealworms. Both had their worms dusted with a special additive that gave them some minerals they might not otherwise get. As they grew, they ate more "salad" (not lettuce!!! my guys love arugula as their basic greens, but will also eat mustard greens or collard greens, though they don't like them and I get dirty looks, I swear). Occasional treats of fruit. There are lists of good foods you can find on this site to help you choose what to feed them.
On the wall???? I'm thinking not. Especially if you eventually use a substrate of sand! I expect any substrate, maybe even just the viv itself, would be way too heavy for a shelf hanging off a wall. Best find a table of some sort that you can put the tank on.
I've probably missed a dozen things, but these are the basics that come to mind at the moment.
Good luck! Beardies are a great deal of fun and actually quite intelligent. You'll have fun with this.
