Not sure what the exact criteria are to pass the class 2 or 1 for that matter but they usually look for well controlled asthma. ie no admissions to hospital, using the ventolin/salbutamol (blue inhaler) infrequently etc....
I have friends with their class 1 who are asthmatic and had no problems passing - sounds like you have a very mild form and should be fine.
If you want to work out your PEFR then for males:
http://www.ncemi.org/cgi-ncemi/edcalc.pl?TheCommand=Load&NewFile=predicted_peak_expiratory_ flow-males&BlankTop=1
and females
http://www.ncemi.org/cgi-ncemi/edcalc.pl?TheCommand=Load&NewFile=predicted_peak_expiratory_ flow-females&BlankTop=1
Your PEFR shouldn't be too far off the predicted on the day of your test.
Good luck