Hi and welcome Christine,
There is lots of info
here on visas and how to immigrate to Canada. We have nearly moved there twice before, the most recent being 2 yrs ago, instead we moved to the USA. I would advise against moving without a job unless you have loads of money that is, it costs A LOT of money to emigrate (£10K+). If you wanted your children to move with you, make sure you check the cutoff age, your eldest especially may need to qualify for his own visa independently. It's very normal to not hear back at all when applying for a job. I would avoid paying out to agencies as they are likely to just take your money.
Where in Canada are you looking at?
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