You'll need an enclosure (obviously
). An adult dragon needs a tank with at least 6-8 square feet of floor space and at least 18 inches in depth. If you're looking at an aquarium type tank, this works out to a 75g (4 ft long x 18 inches wide) or larger.
Heat lamp and fixture - you can use a regular lightbulb or halogen flood light for your heat bulb. They cost less than the pet store basking bulbs and do the exact same job. Really all you need for heat is a bulb that puts off bright clear/white light (not red) and enough heat to get your temps to the right area (100-110*F basking, 80*F cool side).
UVB bulb and fixture - you mentioned you're in ireland so I'm not sure which would be the good UVB bulbs over there. If you ask in the enclosure forum hopefully someone will be able to tell you. I know that there the best choices are the reptisun 10.0 for a flourescent tube UVB (reptiglo 8.0 and reptisun 5.0 are decent as well), and then the Megarays (see
http://www.reptileuv.com) and the T-Rex Active Heat Flood bulbs for MVBs (mercury vapor bulbs). Either of these are good options for UVB exposure, it depends on how much you want to spend and the design of your set up. Avoid compact bulbs (look like energy saver bulbs) as these have a variety of issues with them, and any ESU or R-Zilla bulbs as these are junk.
Substrate - with a baby, something solid like paper towels, nonadhesive shelf liner, or slate tiles that they can't swallow is best since they like to lick everything and their digestive system is small and prone to impaction. As they get older/larger it becomes safer to put them on washed and sifted playsand if you so desire.
You'll need something to keep all the live bugs in that you'll be going through. A growing dragons eats about 50 crickets a day, and it usually works out best if you buy the crickets in bulk to save yourself a bit of money. Crickets can be kept in a big plastic tub with smooth sides, or in a 10g glass tank. They can eat the same greens and veggies you give your dragon, dragon pelleted food, oatmeal, and commercial crickets food among other things. Make sure the container is well ventilated since good airflow is required to keep everything dried out (if it gets damp the smell goes through the roof and the bugs start dying off).
Other than that, the other basic you'll need is a basking spot for the dragon and maybe some stuff for him to climb on. This doesn't have to come from the petstore though - you can use rocks and branches from outside as long as you clean them first, or be creative with things you have around the house.
secondly my house here in ireland is freezing at the moment winter and all and i dont have much in the way of heating.. during the night when the heat lamp would be turned off would a heat mat in the tank be enough to keep it at a decent temperature, or would something more be needed?
We usually recommend a ceramic heat emitter for night time heat. The problem with heat mats is that dragons are designed to feel heat coming from above, as well as to feel their overall body temp - not particular hotspots. As a result, if the mat gets too hot, the dragon can be seriously burned on his feet and belly. With the ceramic heat emitter, this isn't an issue since it screws into a light socket over the dragon's head.
ive read up on here about substrates and such... i would like to use playsand or tiles if not.. how bad is it to use sand ive read mixed thoughts i know how bad calcisand is so ill stay away from that anyway. also the tank im thinking of buying is quite high so id like to use the sand to raise the ground a bit.
I wouldn't use sand with a baby dragon due to their habit of licking everything, as mentioned above. Once the dragon is older so that his digestive system has grown and isn't as prone to impaction, and he is a better hunter (i.e. he doesn't get a mouthful of ground every time he goes for a bug) then you could try the sand. Some people here have used it successfully. Honestly I've never tried sand, although I am thinking of adding a sandbox to my dragon's tank so that she has the opportunity to dig around in it if she wants to. If you go over to the enclosures forum and do a search for "sand" you'll come up with many people's opinions on that topic.
Hope this helps