if you tell them you smoked drugs on the form, youre medical ends there
I'm not sure if that's strictly true. I'm not sure what the exact situation is regarding class1, but information gleaned from this forum suggests that an admission to drug use would, at the very least, spark a referral to a psychiatrist for specialist assessment.
Lying to your AME? It's a bit like sleeping with your best mate's mum. Seems like a good idea at the time, but bound to trip you up in the end.
Safe flying