How quickly can I divorce my tunisian husband? Our marriage is registered in uk but he is still in Tunisia

I doubt Tunisia would have anything to do with it. I'm American and am not sure of Canadian laws or what province you are in. In the US there are means for divorcing a person who has abandoned you or can't be found or won't respond and I'd guess it's the same in Canada, so go see a lawyer. I would not focus on how fast you can divorce no matter what the countries involved are - it's one of those things where getting it right is far more important than getting it fast. If he's out of the country and you're separated anyway, just be patient with the process and make sure it's done properly.

Do you have children?

She's in the UK - the United Kingdom - not Canada.

You refer to Provinces and Canadian Law - am I missing something?

Yeah... that was kind of goofy of me... nevertheless, my guess is, in answer to her question, there is probably a means for her to pursue a divorce in the UK even if he's not present or cooperating but she'll need to find legal representation to find out for sure. And, I still think focusing on how fast she can divorce should not be the priority - if anything, when people divorce, I think they really need to slow down, take a breath and be very careful as already under duress, we don't always make the best decisions.

Excellent advice from dontknownuthin. Slow down and take good legal advice. It depends in which part of the UK you reside. Scottish law is very different form the family law in England/Wales and N Ireland is different again.
Yes, there is a process for divorcing when spouse is unable to be found. Seek advice from divorceaid.co.uk which specialises in international family law.

If both parties are in consent to get divorced; both sign the necessary documents and at least one of them will fly to appear before the judge on the day of the court hearing, they can file for a fast divorce by mutual consent pursuant Divorce Law 142. You can read more at:

The U.S. Department of State on divorces overseas;
http://travel.state.gov/law/info/marriage/marriage_641.html

The Fastest Way to Divorce Worldwide
Www.dfastdivorce.com