MBB application help?

Hey! Long time lurker here and now I guess I'm finally going through the process of applying, I thought I should ask a few specific questions (would be helpful if you're from the UK or are aware of how things are done in the UK).

I go to a semi-target university in the UK (I think the leaked documents of how MBB screen put my university at tier 1 (after the known priority universities) but I'm not sure if that's anything to go by as I'm seeing different things). I have had quite a bumpy road throughout my academic life (major extenuating circumstances) but despite this I was able to get top GCSE grades compared to others in my school (A/A* grades where the average grade was a D); however, long story short, things got bad during A Levels and I'm far off from the AAB requirement that I see people say is the minimum required to get in. How true is this requirement and would this be an automatic rejection? Oh and I know they do RARE recruitment so I'm from an underprivileged background and fit a few of the questions they ask if that helps.

I have a good "GPA" and I think my extracurriculars are good. I feel as though any of this won't matter if I can't get past the initial screening anyway?

I was also wondering if I should put something on my CV that I haven't done yet? I usually wouldn't until I had a few weeks of experience on something but I don't have any direct consulting experience. I recently have been accepted as project head for consulting (it's a competitive society in my university that take on real consulting projects with companies) so I'll be leading a team through the various projects I'll take on throughout the year. However, this does not start until the end of this month/early February so I'm not sure if it's wise to mention it? Or should I leave it and in the case I get interviews (even for non MBB ones) somehow slide it in into my answers as I imagine I'd be working on the projects by the time interviews are being held?

I was also wondering on whether to put my ACT score? I had to take it once due to my school choosing random people to take it but I don't think it's MBB level good? It was a 31 overall with a 33 in science and maths and then 28 for both reading and english. I imagine it's not needed at all for London as majority of students here don't do the ACT or SAT but I was thinking of putting one of my preferred locations in one of the American locations (thinking LA, D.C., Chicago), and perhaps Canada (Toronto). 

Please be as honest as possible. I've seen people be really honest on here and would like the same!