Assuming the balcony is above ground level, you will require a 1,100mm balustrade to comply with Building Regulations. There are many options ranging from simple steel designs at about £125 to £250 per m installed plus, stainless steel with glazed panels at £350 to £500 per m and frameless glazing, the real luxury option. Your best bet is to browse the advertising in Build It and search the internet and speak to your local steelwork fabricators for advice and costings. Your architect should also be able to help.