How useful are online courses/work experience for Law applications

It all depends on how you describe it in your PS. For example, I did a law work experience on Springpod, which obviously doesn't seem like much. But I got to talk about how I learnt about the distinction between primary sources and secondary sources. I got the offer from university so it clearly worked. However, as you said, the bulk should be about you in-person experience.

ah so talking about some specific things you learned online could help you stand out yeah?

Definitely! That's exactly what you're supposed to do for anything you choose to mention in your personal statement. For example, I did (and am still part of) a work experience run by Clifford Chance called ACCESS. Instead of just saying I took part, I mentioned how I learnt about due diligence and commercial awareness. Same goes for a human rights project I did with QMUL - I mentioned how I learnt about constitutional law and the intersect between law and politics (then followed up on this through reading on the Belmarsh case etc etc).

that's really helpful bro I appreciate you.