Your husband would have to sponsor you for PR. You can find a lot of info on the family class section here:
http://www.canadavisa.com/canada-immigration-discussion-board/family-class-sponsorship-b5.0/As you are living abroad, he would have to provide some proof that you both are planning on moving to Canada once you get your PR. This could include having a job offer, having arranged housing etc. You could also leave it until he actually moves to Canada. With a British passport, you are visa exempt and can go with him as a visitor and apply for your PR then. It would be best for you to use the outland application (not officially living in Canada) even if you wait to apply until you are there. Current processing times are 66 days in Mississauga, see
http://www.cic.gc.ca/english/information/times/perm-fc.asp and after London takes about 8 months to process 80% of the cases, see
http://www.cic.gc.ca/english/information/times/perm/fc-spouses.asp#europe so you will most likely be faster than that. If you apply while you are living in the US, you can also opt to go through Buffalo but they are slower than London.