No mate I'm a boat builder by trade but can turn my hand to most things.
Have just bought the over centre latch for the closing system it's S/Steel with a 3500lb rating so should be strong enough.
Must admit that pic isn't a very good quality one will get another later when it's a little more progressed.
Nice work Sam,its coming along nicely. I like the DIY projects as well, but working away at the mines and 2 children under 5 doesn't leave me much time at the moment for this sort of stuff.