The 8+

[wahwahwah]

Is there any way of getting my mits on past papers for a specific school or do they use generic ones for 8+ entrance exams?

Have you asked the school? Most should be happy to give you an example. If it isn't a formal entry they may just assess the child on the basis of what the class is doing currently.

I agree with Ladymuck. Ask the school. If they will not let you have a real paper, then they will probably spell out very clearly what is expected of a child at this level for entry to their school. My DC's school gave me a full list that said things like "Tell the time in analogue and digital", "2, 3, 4, 5, 6, 10, 11 times tables" etc.

Go ask them, don't be shy!

My understanding is that for the 8+ they are looking for potential more than what they can actually do. Lets face anyone can teach a child times tables however can they apply them? You could ask the school however I would be very surprised if they give you a paper. They will simply be 'testing' what they should have covered under the national curriculum but will also almost certainly do verbal and non-verbal reasoning. Good luck.

Few schools in London give past papers. Kings Wimbledon has them on its website and Latimer (7+) gives one a peep at the tour. But they all should give detailed curriculum guidance.
Where are you trying for?