Well i consider London a food meca in Europe ( obviously not like france , or italy ) but yes their still exists fine dining restaurants in London.
My chef got a short term scholarship in le cordon bleu , and she said their is alot someone can learn from working there a bit.
Also im pretty sure you can fine a job , depending on your resume..... don´t expect it to be easy though , im sure there are various of young culinary apprentices in London , along with culinary grads , so don´t expect to be working the line so quickly , not that it can´t be done.
Also how will you be staying there? Are you getting a work visa , a tourist visa , etc....
Because im pretty sure depening on the restaurant , they wont hire someone so quickly ( and pay that person so well ) if they dont have the papers explaining their status in the country.
My honest opinion ?
Well i hate to be the bubble burster , but if i was in your shoes i would work the field in Canada a bit longer , and wait till i get older , wait till maybe Europes unemployment rate is better , and wait till i have legal papers, along side with a potential job offer.
Canda does have alot of high end places to work at , and well not just high end but decent mom and pop places as well. You can find different cuisines in Canada , and actually work under some great chefs. I dont know what part of Canada you are in , but i would probably reconsider my plans and stick awhile longer and wait for at least another year or 2 until more experience is gained and more $$$ in my pocket.
Maybe you can get a great job , get papers , compete with the rest of the crowd , and work your way up , but again , you will be in another country , you are young , and well , getting permanent or part time residence will be difficult ... remembering that their is a higher risk of failure partaining to this decision , at least that what i think , considering the amount of information you gave out so far.
P.S. i noticed your moving due to personal reasons , remember i answered the questions not thinking about that , and solely stated my honest opinion , nothing against your at all , its just how i see the situation.