Some people say that if you hook up the mains end first, the electrons can drop out onto the ground at the other end while you're trying to hook it up to the van...Question 1. So, a very long time ago I had my old LT (not quite horse drawn van), and can't for the life of me remember whether I hook up to the van first and then the mains or visa versa?
In reality there is little risk from hooking up at the post first, because site electrical installs (in the UK, at least) are very tightly regulated. But if you're very risk-averse, you should hook up to the van first and the post last.
Unfortunately a photo doesn't give any real idea of dimensions. All you need to do is go onto Calor's UK website and it will tell you the sizes of all of the cylinders. The regulator that you have is for a Propane cylinder, not Butane.Question 2 . I need to get a Calor gas cylinder for my two hob cooker, but based on the space (see photos), what size/type do I need?