Thanks guy's for the reply's, and yes no win no fee but the £480.00 would need to paid for the surveyor, which is non refundable, this is what made me think it was a scam.
Our workshop was new in June last year, now I am sure that we have to pay total area including floor to roof area which it is quite a tall unit, other than lights and the occasional car on a ramp we have no use of this area.