Are you currently married? Is there an Order in the UK that requires him to pay child support?

In which Province do you currently reside?

I believe that, under the provisions of the family law act in BC, you will be able to commence proceedings in BC to obtain a child support Order in BC. Once you have that, you will then need to attempt to enforce it in the UK. It shouldn't be that difficult and I anticipate that the biggest hurdle will be serving him in the UK. If you use a process server, it should be relatively straightforward. Once you have your BC child support Order, FMEP will likely be able to assist you with enforcement in the UK. However, FMEP are about as useful as a chocolate fireguard, so you will have to keep on top of them.

Good luck!

The Canadian immigration site has nothing to do with child support. You need a family lawyer or to petition the family court without legal help. CIC is not responsible for family law matters.

What I would do is to copy Almost Canadian's post number 6 into the body of an email, stick quotes around it and add some framing text such as:

I need to do the following and am looking for someone to act for me. Please let me know if this type of work is of interest to you and approximately what it would cost at each stage.

I'd then google for family lawyers close to me and send them all a copy. If any responded I'd ask for a free half and hour with them, visit them all and ask the one I felt offered the best balance of competence and rapport with me to pursue the matter. I'd then step out of their way and await news (and bills).

Sounds good advice. But for "if any responded" read "the one that responds" as you're lucky to get one who does.

This is good advice. I'd suggest that the OP's first port of call should be the Lawyer Referral Service offered by the Law Society of BC. Details of it are here: BC Lawyer Referral

That's how I found my, corporate, lawyer. It took me a couple of hours to write out what had to be done and only a few minutes to send it to all the law firms in southern Ontario. Just like asking for a quote for the garage roof or for a new car. A young associate at a big firm responded and we went on from there. I'm sure there are lots of firms that are too grand to look at unsolicited email but that's their loss, someone will be hungry for the work.

I've done it for realtors, roofers, lawyers, dentists...some more than once...lucky to get one response, rarely a second and often none.

Very different for repair people. They respond. Hungry I suppose.