The towing question is fraught with MG forum urban myths.
In fact the only mention about towing the car that I've found in official literature is an admonition not to tow the car with a rope or chain. This is for the simple reason that a rope/chain would damage the front of the car because the eyes are really low on the subframe.
Towing the car with a dolley, A frame or a bar is OK.
In law, only a vehicle with a Gross Train Weight stamped on the vin plate SHOULD tow a trailer in the UK. This is the maximum weight of car and trailer combined.
I think in reality that you'll find a lot of cars towing caravans which don't have the required vin stamp. So the MGF/TF is like a lot of cars it doesn't fulfill the legal requirement to allow you to tow a trailer.
This is a useful page