BP limit for a JAA medical is "consistently over 160/95" (if I remember correctly). He/she might give you a stern look, but if it's under that figure you've passed. When I did my initial Class 2 medical I'd cycled there, and was late. First thing she did was take my BP - through the roof, strangely enough. Calmed down by the end of the proceedings, so medical issued no problem.
Usual rules with BP - if you're overweight, lose some. If you drink too much, cut down. If your diet has a lot of salt in it, cut it out. If you smoke, stop. I did all the above (except for the tabs, which are still on the to-do list) and found mine dropped quite a notable amount.