On 13 May, 21:48, Jules Richardson
wrote:
Right, I've had three pallets of patio blocks sitting around since last
year, and I really must get around to doing something with them...

I'm assuming a layer of sand (about an inch) immediately beneath the
blocks (and a layer of weed matting) - then x inches of gravel.

a) What's a good type of gravel to use?

None. Do it properly with well compacted "hard core", see
http://www.pavingexpert.com/ for the correct terminology.

MBQ