To prove your age at the event, you'll need to have photo ID with you. Without this, you'll only be able to receive an under 18's wristband.
In addition, for both physical and online tournaments, you may be required to show photo ID to the admins before competing where the tournament requires it.
These are the only acceptable forms of Photo ID for proving 18+ age at epic.LAN events:
Resident of UK: Passport, Driving Licence, Accredited Identity Card (bearing the PASS logo, like Citizen Card)
Resident of Europe: Passport, Driving Licence, Government provided ID card
If you don't have an ID, you can check out CitizenCard and can apply for it online- this can also be used as online ID using a QR code.
In all cases, these must clearly show a photograph and the date of birth. These can be asked for at any time during an event.
IDs supplied by universities, colleges, schools or student union cards are not acceptable.