OK folks, I went up to the Aquarium Design Centre in Glasgow, i looked at a corner unit they do which holds 17 gallons but has a far better surface area, the dimensions are as follows from the back to front on each side is 18" then small angles of 6" and then the front glass measures 17" across, the height of the glass is 18" . The cabinet and hood will be in black ash finish, i will then have to make a choice of an internal or external canister filter plus lighting. I do have a photo of the glass tank without cabinet but i dont know how to upload.