Aerospace Battle Manager/FC or whatever it is called tomorrow is traditionally thought of as a much more demanding role than ATC, but that is simply because you have to have the basic three-dimensional aptitude, which many people simply don't have to a high enough level. Years ago FC training used to have a phenomenally high chop rate, at about 90%, but they sorted that out in the mid 90's, so now you have a decent chance, if you start, of making it to the end of the course. So don't be swayed by historical stories of the impossibility of FC training.
The traditional description of the difference between ATC and FC is that ATC try to keep aircraft apart (ie fulfil a basic safety fuction) and FCs try to bring them together (ie manage the airborne battle). There might be some appeal in doing one or other of those, but I'm not sure it gets you far. There are many more posting opportunities for ATC, fewer for FC and FC postings tend to the more remote. There are easier, but not easy routes into civvy street with ATC expereince, less with FC.
You probably need to get to Boulmer or 1 ACC and check out the FC/ABM job, it is a pretty highly specialised job and I guess you either love it or hate it.