not sure about the regular aspect but certainly if the police stopped you they would say they've caught you commuting to/from work and therefore have no reason to suspect its just a one off thing.

personally if you really want to save £30 by taking off the commuting then just dont use it for work at all. if you want to drive it a bit more than maybe use it more occasionaly for shopping or splash out a bit more and go on more track days but that does the opposite of saving you money lol.