You only need weight training in my opinion.
I haven't done any cardio (if you discount my 6-8minute warmups) in the last 18 months. I train 3 times a week (squats, deads, bench) following the 5/3/1 routine. I do 3-4 accessory exercises only, and these are bodyweight as far as practicable (pullups, pressups, dips, depth jumps etc). Each session takes me around 2hrs including 20mins warmup/ stretching, and 20minutes warm-down/ static stretching.
One thing I would recommend to you is what westside calls GPP (general physical preparedness) - on each training day one of the accessories I perform will be a heavy-weight-endurance type exercise, that will really get my heart pumping. For me this is usually either Farmers Walks with a couple of 100lb dumbells, or powercleans with around 150lbs (both for max reps/ time)
All told, my 'activity level' is about 4-5hours a week tops. I do paleo and leangains (IF), my bodyfat is currently around 9-10% (despite being on a constant calorie surplus :P), and if I want to run a 10k I know I could. Don't see the need for cardio or 'circuit' training :)