USA, Canada / I want to go to Montréal , need advice [5]

cześć , hi , salut

I'm a young polish student , currently in the UK , I speak both english & french and would like to go to Canada for a work experience / internship - I only have 6 months from April to October then I have to come back and complete my LLM

it seems quite impossible to me to find a short-term job ( 6 months ) in Canada , I've never been there before !
thats why I need your help : is there a chance to find a temporary job online ? or it is better to go through any employment agency ? or work&travel program ? or maybe come to Canada first and look for a job there with my tourist visa but I think its illegal ,?! also - I will need a work permit and as far as I know I need to apply for it before I enter Canada , to apply for it I have to find an employer first but nobody wants to hire immigrants if they have no work permit so its all very complicated

you might know more about it and I would be grateful if you could give me some tips , advice , maybe its not so hard as it looks

thanks for any info , advise
merci pour toute info utile , conseil
dzięki za każdą radę , informację

Izabella