well, if you are a British national and you are using British passport, then you don't need VISA to travel to Canada. All you will need is the introductory letter with some sort of reference codes from the canadian High commission which you will present to an immigration officer at port of entry for your study permit to be affix into your passport (i.e if it has been approved).
I will suggest you double check your mail box well, including your spam mails, because based on the information I read on their website, they normally send the introductory letter through emails.
If there is nothing, you might have to wait for them to reply the email you just sent them. I think they will reply in couple of days, if not then I guess you must plan of going there yourself.
Which part of UK are you from?