Every club I've been into they take IDs, usually driving licenses (can be provisional or full) and put it into a machine which shows the age of the ID.
Some machines do face recognition too.
They would probably be suspicious if you attempted to give them anything apart from a driving license (or perhaps a passport / national ID card).
There will be Freshers events for under-18s, but don't expect a club or other 18+ event to let you in.