I’ve been a Club member since 1986, and the only way you can be sure if being granted access in addition to merging the standard access rules if you are under 18 is being accompanied by or accompanying a person over 18. Authorized Users aren’t are allowed guests, so that’s another possibility for the OP.

My suggestion is to show up at the admission desk, act relaxed, present proof of access qualification and try your luck. If they ask to see proof of age and deny you, there’s no way around I can think of.