I'm based in Sweden, so TPMS are not required by law. And finding tiers with them are harder then withoutIf it is like the LEAF then you get a yellow tyre warning message on the dash but the car drives normally. Obviously you don't get the safety feature and it would be an MOT failure.
Yeah seems to be a difference in price as well. Price seems to be 200-300£ for fitting them in all 4UK law is clearly different, as although TPMS are not required if the system is fitted the law requires it to work.
A set of pattern TPMS costs about £80 so personally I'd fit them, but it's your choice.
Aha. Do you also have two sets of tiers?4X TYRE PRESSURE TPMS FOR RENAULT MEGANE III LAGUNA MEGANE ZOE 407000435R 433MHz | eBay
Not official but effective.