@Suggsy congrats on the milestone, welcome to the club 8)
I would repeat some of those above, Skills course, Alps bike holiday, somewhere great with the Mrs.
FWIW getting two tickets for England France will be difficult and £700 a pair at a guess. If you do make it drop me an email and we’ll have a beverage to celebrate if you wish.
EDIT: Also I made a list of 50 things to do in my 50th year, I never managed to complete it (not least due to knee injury which meant all of the active stuff had to be put off), buts its a great way to make it a rolling celebration with friends and family. My list had biking, skiing, walking, reading, cooking, travelling, reading things to do. Its fun just to make the list. Idea was stolen from Carol Voerderman who did something similar