As a general rule, 1 tonne of sand will build about 18 square meters of 4" brickwork. Thats 1000 bricks and 12 bags of 25kg cement.
No matter the bond or thickness, 1 tonne of sand = 1000 bricks = 12 opc.
If the brick has a very shallow, or no frog at all then you may get a few more bricks...