Where in Leeds are you? When I was knocking out gates and railings I used Stansfelds in Meanwood for the steel - they are expensive but don't turn their nose up at delivering one or two bars. Steel Supplies in Doncaster are good, again don't mind delivering small orders and are probably a bit cheaper than Stansfelds.
For scrolls etc you can't get better than DC handrails. Spot on service and next day delivery.
Leeds galv for powdercoating and galvanising.