Should I do a PhD at an Ultra-Target University if I Want to be an IB Analyst?

So I know a lot of you are busy and I'm not going to waste your time.

Here's a brief background so you understand my situation. I'm currently in the UK, where I was born and raised.

• Partied too much in college and received shit A Levels (three Cs). My own fault entirely. I'm not going to give a would have/should have/could have bullshit story
• Went to a non-target polytechnic university, got my shit together, and finished first in my class with a first class honours BA in political science
• Currently attend a semi-target university studying an MA in international relations, where I'm predicted a distinction (highest grade) and have taken optional modules in advanced statistics and macroeconomics, as well as playing an active role in the banking society and completing the Bloomberg self-certification course
• My tutor is an alumnus of an ultra-target (think Oxbridge/LSE) and is strongly recommending I apply there for a PhD in international relations, due to my interests and strong academic performance (post-A Levels)

I have no direct IB experience, but I am currently applying for summer and off-cycle internships at BBs, MMs, and boutiques. I have also purchased the IB interview course from WSO in addition to practising building DCF and M&A models for companies in Excel.

With regards to networking, I am currently connected with about 15 analysts/associates at BBs and MMs on LinkedIn and I am being proactive with outreach. I have a few friends in my university's banking society providing me with guidance too, some with friends and family in the industry.

Now you know my background, I have a few questions:

1. At this stage in my life is IB out of reach? Are my A Levels too shit and should I just give up?
2. Will a PhD at an ultra-target (Oxbridge/LSE) be beneficial to me when applying for an analyst position?
3. Is there anything I can do to improve my candidature? I don't care what it is; if it gets me closer to an IB position I'll do it.

Thank you for taking the time out of your hectic lives to read my post. I know you'll be brutally honest and won't sugarcoat anything, which is why your opinion is highly valuable to me.