Is there any where i can read up on the regulations? I do remember some of them when i done a balcony at college.The strength of a gate can be dependant on the design as much as the material, if you have some horizontal framework across the middle for example, it in itself can add rigidity to the outer frame.
There is a safety ruling for the distance between any uprights, you are not supposed to be able to pass a 100mm sphere between the bars, stops you coming home and finding a hoard of kids with their heads stuck in the rails.
Railings also have a regulation height if there is a drop the other side of them.
Thats the sort of info you need for the problems I mentioned earlier regarding liability, even if you are making for family...other members of the public use them and in all probability nothing will happen but if it does then it's scary what problems can follow and the resulting cost.
There was a case a couple of years back in Glasgow where some kids were swinging on a gate and it came off injuring a young lad, the maker was held 50% to blame because the fittings were deemed not to be right for the wall material, if I remember right he was hit for a fair amount of compensation.