I agree with the good fella above me. A PPL doesnt necessarily have to pay for his share of a flight. If for example, my friend owned an a/c and was going on hols..he could ask me to take it for a spin and it'd be free..I'd be doing it as a favour and it'd not cost me anything.
Similarly, if I travelled say to Duxford on business, then my company could cover the cost of hiring an aircraft - as long as I'm not getting paid TO fly...I get a salary as a sales man or similar..I'm just using my ability as a pilot to get me there. No problems at all with using a PPL to do that.
I suspect one of the major probs would be weather...to go places regularly and on time you'll be wanting an IMC or IR rating with the British climate.
But having said that..don't let it put you off...any excuse to get extra hours and (and at less personal expense) has to be applauded