As stated at the moment we don't need IDP or green card, although I notice recent car insurance renewal does mention asking them for a green card (free) for European use. May be worth checking this with your insurer.
As for IDP, my comment was probably influenced by my habitual pattern of being in France from mid September until end October each year - if followed this year would probably need the IDP unless we have yet another delay or even cancellation of Brexit.
I'm sure the information will be on Gov. website, but as I understand it you need you current driving licince, passport photo, and £5 at specified post offices ( again search online) and that's that. However, in years ago you needed a different version for France and Spain which probably means two IDPs and there may be further requirements for trips to multiple European countries.. CMHC etc. sholud have details.