what percentage of the spraymalt is wheat? does it say on the pack? im sure wheat is meant to aid the head on your beer, personally I would give it a try, you would be better with extra light spraymalt but its 6 and half a dozen. try brewing it short to 19/20 litres. I've brewed close to 20/25 kits, the general rule of thumb is keep everything clean, bung it in, and it will taste good.
have you brewed many kits before mate?