What can you do with a level 3 in coaching?

In my opinion, its all a load of modern business babble and has no practical application in reality. It's going to be a bunch of time spent on half baked theories of organisational psychology and management that's been plucked out of a variety of dubious self-help books. A bunch of total nonsense about transformational leadership, skill/will matrix and so on. They might even throw in a bit of six thinking hats. On top of that, you'll be sold a bunch of trash about coaches vs mentors and how a good coach doesn't need to know anything about the subject matter, but facilitiates and empowers the student. Its rubbish.
However.
That does not mean it won't help you get a job, because frankly half the western world has bought into this total bunkum, and there's a fair chance that any large organisation will also believe in it and might well take you on to spread it around their workplace too.

Thank you. I was wondering what kind of jobs I could do with it? Would jobs that aren’t to do with sport but are with children find it to be good when applying?

If this is the general L3 coaching / mentoring that I think it is....it doesn't have to have anything to do with sports! The whole point of this movement is that if you are "trained" in coaching you can progress anyone in anything without knowing anything about it! So for example, a kid comes to you and says they want to be an astronaut. You studied Fine Art, and know absolutely zero about astronauts - it doesn't matter. As a trained coach, you ask them a lot of open ended questions and some how, they find all the answers themselves, get super motivated and end up becoming an astronaut.
Sounds dubious? It is.
But as I said, half the large organisations in the the UK have bought into this, so chances are it doesn't matter how silly the whole thing is, if you have the qualification, it may well give you a boost with these large employers. Just speak with absolute confidence about it and how important it is - and if the person interviewing is into it, it might go in your favour.
Just one warning - make sure you take it for what it is (complete fraud). Do not under any circumstances ever ever ever get into the whole professional lifecoaching / coaching gig. That is effectively an MLM scheme designed to extract money from you.