Target Uni VS More Relevant Degree (UK) for getting into High Finance

Hi,
I've already secured and got my place at the University of my choice (Newcastle) to study Computer Science.

However, one option I really want open, is getting into high finance (investment banking etc) and for this I would most likely need to go to a Target. I'm not entirely sure about this, and it seems I would need to go to a lot of effort to get there, but it all seems worthwhile.
So my options are:

Newcastle - Computer Science, work hard to get good grades then do an MSc in some management or some shit at the top 3 uni or something

Defer my place and go to either of these: Target - ITMB Something else (Warwick/UCL/ etc) Semi-target - Computer Science (Nottingham only place that I have relevant A Levels for.

Now, could any of you offer me any career advice?
For me, it would be cheaper, easier, closer to home, for me to do what I have already chosen at NCL, but I don't want to rule out the possibility of getting into lucrative careers in IB.
Thank you! :)