You're probably right - but for £15, this should at least make the basis of a decent prototype. And then, much like yourself, depending on experience, look to replace with something a little more sturdyIf you can get heavier ally than 2mm it would make sense, mine is around 2mm and will probably end up being remade if I do any more off roading. Might as well future proof it by making it strong enough from the start.
Talking of more sturdy - is the thickness of the alloy needed just a bit of guess work? I've seen various thicknesses of material being used - all likely in various grades of aluminium alloy. My impossible question is "what's best"?