For some reason the bonnet has decided bro not open. I've searched and it seems one way is to take the os wheel and wheel arch liner off and then kind of grab the cable from underneath.

 

Is this the only/best way?

OK, sorry if I'm pointing out the obvious but are you sure the problem is not between the release lever and the cable? in which case just pull the cable directly.

2 hours ago, Octy0GG said:

OK, sorry if I'm pointing out the obvious but are you sure the problem is not between the release lever and the cable? in which case just pull the cable directly.

Would I need to remove the trim around the release handle first?

As per this old post, it seems that there is a joint somewhere in the cable which may get detached from the cable lever so if not succeed with 2 people (one pulling the opening  knob and other lifting  the bonnet) and or try pushing bonnet first and then  lift.... it would be a job of removing the left wheel and one - or two plastic inner to find the cable and try that way.

 

13 hours ago, Aj77 said:

Would I need to remove the trim around the release handle first?

I don't think so but have to confess I'm not 100% sure and can't check as I don't have an Octavia 2 now.