As others have said, CCNA & MCSE should be your first port of call. If you plan it right, i believe you can do the MCSA and then MCSE if you make the right exam choices, which would help if you get bored easily (i.e. i started my MCSE in 2000, got 4 of the exams done, then couldn't be bothered to go any further with it) and mean you could at leasyt have a qual whilst you take a break. Try the CCNA stuff too, a couple of the lads who work for me have done self study, after completing the books and doing a small mock test in-house i than arranged for them both attend the training courses and one guy passed with 100% and the other with high 90's. both are now working as Junior Network Techs.
I see a lot of talk about CCIE, to be truthful i would be suprised if big financial houses would employ them, i would be more of the opinion that they would sub-contract work at that level to one of the bigger network suppliers with in-house CCIE guys, or even have an outsourced network supplies contract.
Doubtful tbh. A big financial house would more than likely already have CCIE if that was the route they were going down, but i would expect most of the larger fiancial houses to outsource that level of work to a specialist company. CCNA + Exp is more than enough to get you working in a NOC or 2nd level tech team in a FTSE100 company.