The time it takes to get a fiance visa depends on the country where you apply for it. In Canada I am sure its a lot faster but I guess not as fast as 5 days. You should provide a couple of weeks for it at least to be on the safe side.

Yes, you can 'give notice of marriage' in your local Registrar Office as soon as you arrive in UK on your fiance visa. It can't be however earlier than 16 days.

No, you don't have to go back to Canada to apply for the 2 years spouse visa. You can do it from within the UK.

I hope this helps.

Good luck

 

Hi,

My Fiance is American and applied for her visa at the LAS embassy. She sent all the paperwork on the 8th of October and got an email the same friday (11th October) saying the visa was approved. She got it on Monday.
I think as long as you have all the correct documents it shouldn't take too long.

 

You CANT switch from a visitor visa to another type of visa within the uk... You need to go back to Canada and apply for a leave to enter (Spouse visa INF4-settlement). Im in the same situation and beleive me, immigration agents at the port of entry gave me hard time about that.