I have mild hypertention, I have turned 40 and my JP said I cant skydive even though ive done lots of skydiving. What can I do?

Ignore GP & jump. Or you can ask your GP why s/he doesn't want you to skydive anymore. Before your chat, search your skydive guidelines for heart disease restrictions. Then start tracking your own blood pressure. How well controlled is it? Perhaps you'll be "allowed" to skydive if your BP is better controlled? One other solution: find another GP who is more amenable to your activities. . .
Ignore it. Go jump. You and I are both skydivers and you know how ignorant the "whuffo"'s can be. Your caregiver is just covering his butt. Hypertension when well-controlled is no contraindication whatever.