Nah, you're good man. Go for the 1st class now, to A. Make sure you can get it and B. it automatically downgrades with time to the lower levels, so no need to get anything lower than a 1st anyways.

The test is a typical physical; pee test, turn & cough(well, dunno what the girls do), eye-sight, hearing(usually they walk behind you and just talk about random stuff, check periphial(sp)), and some breathing tests. I'm 5'10 and same weight, but I was at 230 last year and passed with flying colors. But in reality, yeah, lose the weight, easier now while we're young.