Hi Gazz:
If you truely DO have decreased sensativity on the end of your penis due to a late circumcisian, then you will most likely have to learn other ways in which to achieve orgasm on a more timely basis!
My initial thought to you would be to include prostate stimulation as part of your play! Visit this site:
http://www.highisland.com/description.html and learn about how including prostate massage along with your normal sex will help!
I own one and i can tell you from first hand experience that it works!
You also may need to include other techniques in your sex play. From Nipple play to rimming and more! Having a de-sensitized penis is NOT the end of your sex life, it just means adjusting techniques to take that into consideration!