Not sure if you are interested in walking from the A gates to your C gate (which was implied in a post above). That involves lots of walking when you mentioned not wanting to wander too far. As indicated by mnbp, take the tram from near the start of the A concourse and you won't have any steps, escalator or elevator to deal with. If you take it two stops to the end, you are about half way between the McDonald's and gate C5 when you exit. You could also look for a store between the exit of the tram walking to C5. I believe there are a couple of places that serve coffee so you are not backtracking from McDonald's.