Bit stumped as to how much topsoil or compost you need? Not sure what sort of coverage you'll get from a bulk bag of play bark? Have a look at our handy dandy list here of average coverage for our products.
1000kg topsoil = approx 15 square metres at a depth of 5cm
1000ltrs compost = approx 18 square metres at a depth of 5cm
1000kg gravel = approx 25 square metres at a depth of 2.5cm
1000ltrs bark = approx 18 square metres at a depth of 5cm