Going a bit off topic here but it is releated to what's been said above...
There is no real suitable form of ID until you can apply for a provisional driving license, and most of these IDs for under 18s most places won't entertain them. Oh and the worst I had for a lack of ID was when I was 17 and tried to buy a 12 rated DVD in the Morton Park, Morrisons although the cashier seemed a right mardy cow.
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