Masters for full time?

I've looked this up and the feedback is varied; so currently I'm studying Economics at a non-target British university. I've gained a spring week and also a summer internship within a M&A department at a big accountancy firm.

Say this experience helps me gain a summer internship at a good European or American bank. I perform well and subsequently gain an offer on a graduate scheme.

Firstly is it normal if one wants to take a year out, to take it by deferring the offer for one year after gaining it? Or is it better to finish the graduate scheme and then take one before looking for a FT position?

Secondly, do some firms have a procedure in place to go from graduate scheme to FT position? Or is it common (unless absolutely brilliant) for most places to let you go after the three year graduate position; where you must apply individually again to all places of interest for full time work? If so, is this where/why a lot of people then decide to do a masters degree? Or is it to have good related experience in conjunction with a higher level of academic success? I personally don't want to do a masters degree because I'd prefer to get stuck into work after finishing university but with more and more doing it, it makes me question the procedure of getting into BBs.

If you're interested, I'm more interested currently in going into IBD; despite my natural enjoyment of watching, analysing and trying to judge how macroeconomic factors all interlink and affect markets and different contracts etc, I think I'd be too much of a 'gut instinct' trader once I got into it and therefore wouldn't be that good at it.

Any insight into the procedure would be really appreciated.