I have read the Legislation (god that was dull). They don't specify bull bars or a bars, they are all labelled Frontal Protection Systems, and as such and I quote "Frontal Protection Systems are a seperate structure or structures such as a bull bar or supllementary bumper, which is intended to protect the external surface of the vehicle, above and or below the original equipment bumper from damage in the event of a collision with an object, structures with a mass of less than 0.5Kg designed only to protect the lights are excluded from this definition"
A winch bumper is ok as long as it does not have an FPS fitted to it, i.e. it is only a replacemnt bumper and does not have any other bar fitted to it. I understand that the reasoning behind this is that such a low number of road going veicles have winches and without an FPS attached, will not increase head and abdomen injuries which is where there majority of deaths and serious injuries (for serious read life threatening) and not many poeple die of broken legs.
Actually the fines are max of £20,000 and or 12 months in the clink depending on where the prosecution takes place, i.e. magistrates or crown court.
Hope that helps.