I had my first scan today I am pregnant they tell me am 8 and a half weeks, my partner I last with was the 15th November is this right?

Yes, this could be considered "right". Scans are not 100% accurate in dating a pregnancy, and you may find that your dates change slightly after your next one, but they are generally the best tool available to be reasonably close.

Unless you have a reason to be concerned about the dates, such as the possibility of a different father, which happens for some women, than all is well. Congrats!

Conception dates are estimates based on average sizes and development, they are not exact. If that is the only time you had sex, in a two or three week period, then yes that is it. If you had sex on other dates that was close it could be those.