My foreskin is fairly tight when my penis is erect, the tip and part of the head can exit out of the foreskin however i am unable to get it past the head fully. is this natural or do i need to see a doctor? i can retract it fully when flaccid?

One issue to think about. If the head ever slipped out of the foreskin the tight ring would form a tourniquet and reduce the blood flow. In the worst case scenarios the head could be damaged. It may be worth a trip to your local urologist to discuss your options. A simple office procedure under a local could loosen the ring so it would never do this,

using cortisone cream as lubricant gently pull foreskin as far back as you can then pull it back over the head several times 1-2 times a day keeping it over the head when finished. In about 6-8 weeks the skin will become more pliable and retractable during erection. The other choice is a circumcision