If Timothy is making a private pleasure flight with absolutely no commercial pressure then there is absolutely no reason why he can not wait until the fog has cleared giving both legal and more enjoyable weather to fly in.
If on the other hand Timothy needs to get to Edinburgh for a business meeting then he is profiting from the trip and therefore can decide which is going to reduce that profit more - delay for VMC or pay Nav charges.
Having decided to pay Nav charges why not make the best use of the expense and make use of the services provided in return for payment of those charges - London FIS, Scottish FIS, Volmet, VOR/DME navaids are available at all times.
I think that this is penny pinching to be honnest. How much does it cost to fly the aircraft to and from Edinburgh?
Regards,
DFC