How important is a CV?

I know a CV is important, but right now, during the summer of Y12, I can't find a real use for one. I have had 3 work experiences in A&F, including one at PwC, and in all I was very lucky to not have to provide my CV.

So, now I have all this experience to put on my CV but I'm struggling to find a use for it.

Should I look for more work experience, purely for networking?
Should I complete further, relevant 'activities' (e.g., Excel course or VWXP)?
Or should I just accept that I don't need it right now but will in the future?

Also, if anyone would take a look at my CV, I'd appreciate it.
Right now I'm simply missing the 'Personal Statement' summary at the top – because I don't know what I can use my CV to apply for right now.

I know personal statement (UCAS) is the bigger focus, but I was just wondering about my CV