I'm about to lay some block paving bricks around my front garden as a seperator between two different types of gravel. The soil is very hard and I thought I might get away with laying onto a bed of sand but I'd like to add a layer of dry mix on top just to stabilise it a bit more. Can I buy it ready mixed? Can anyone please suggest something I could buy from B&Q that I could just put down straight from the bag and weather in? It's a straight line run of around 20 bricks and I'm going for the interlocking wavy edge type.