The solution is very simple. If the demand is there an enterprising (highways) coach operator can buy an appropriate trailer for surfboards and run from London to the main surfing resorts.
I have in fact used a “bike bus” in the past for cycle tourists that was exactly the same thing. It was a normal holiday coach for passengers, so the only special expense for an established coach firm would be the custom bike trailer. Moreover, you might think there can be no shortage of holiday coach operators looking for new business opportunities.
Coming next week: a six page thread on why local busses should be equipped to deliver pallets of building supplies