Blah, blah .... if he doesn't check - or drives 10 days after surgery - and then has an accident, you can bet your bottom dollar that his insurer will say he was not covered and the people that he kills or injures will receive no compensation.
Gov.uk website says that the insurer must be informed of any medical condition that might affect driving - it also says "you are not covered to drive until your doctor confirms it is safe to do so". Whether the technically legal position is as you say or not, I don't see how anyone (not even the Stig) could drive safely 10 days after RP and even if they could, it is an open invitation for an insurer to wriggle out of their responsibility.
Bob, my husband's insurer was even worse - they wouldn't cover him for 12 weeks and until a letter was provided by the surgeon confirming he was fit to drive, which the surgeon (understandably) refused to write.