Did mine a couple of months back, and now i cant remember fully...
I beleive theres roughly 4-5 open book multiple choice question papers for CCN1 and one closed book multiple choice question papers.
A practicle work book to work through, working on your usual stuff of regulation 26/9, gas rates, vents, flues and safety control rig. Cant think of anything more for CCN1 apart from the standard tightness testing idea and the safe way of cutting into and soldering a gas line.
CCN1 is a single open book paper, and two practicle based excorcises, one service of a boiler and a install of a boiler(commissioning procedure basiclly)
As for studying material, a corgi handbook is always useful, familiarise yourself with it as itll save time with searching for stuff...Also the G1 pack is useful, you'll get both of these when doing the assesments... You also get all the british standards, but to buy these isnt cheap i beleive.