Sorry, he will have to pay for regular Warfarin at least until (as today's rules stand) he is 60 years of age when all prescrips are free. Depending on his financial circumstances, surely it is money well spent to avoid a blood clot. In addition he consider the NHS (?) total costs to that of his
valve-insertion versus final prescription cost. He is not forced to submit his prescriptions but this would be stupid but that choice should clear his mind regarding the costs.