Hi

preparation is the key

lay 6 inch of scalpings over a black plastic membrane
hire a wacker plate and level the area and firm it down
after that i find paving slabs 450x 450 the easyest to lay
use a dry ish mix sharpsand to cement about 5 or 6 to one
make sure it level
and bobs your uncle
i tend to tip each slab just slightly and groute using sharp sand so any
water runs off and doesnt sit on the slabs
hope this helps

oh work on about £15 £30 a sq mt for the slabs and base and you wont be far
off thats using B+Q or Wicks Slabs

regards
Dave