is Economics at UCL good enough to go into a management consultant like Accenture or McKinsey or one of the top IB like Goldmann, Deutsche bank?
Yes. But one really should describe them as "technology consultancies". You need to decide what sort of a job you want, and do some more research, before asking us any more questions really.
McKinsey and Bain (both of which who you have mentioned) are top-level strategy houses and are almost certainly beyond you (not a slight on you: they're almost certainly beyond everyone). UCL is a black mark on your application to both as within the UK the only universities that will add value to your McKinsey/Bain application are Oxford and Cambridge; however, like I said before, UCL isn't "too bad" and so you could still get an interview with strong ECs and work experience.
What sort of aspirations can I expect with:
Maths - A
F. Maths - B
Comp - B
History - A
BSc @ University of St Andrews
Computer Science, Economics, Maths.