hi hun and welcome!
Legs, my fav thing............................
You don't need a huge amount of time in the gym to get your butt and legs all lovely again if you train with enough intensity.
You will also burn a HUGE amount of calories.
Just to give you an example, I have a heart rate monitor that is programmed for me......
one hour of cardio on the x-trainer, usually about 500 kcals
45 min of my leg workout- 600 kcals
Also with doing weights, you keep burning calories a lot longer after the workout, and building muscle gives your body the great shape.
Muscle is also more metabollically active, so more muscle will use more calories.
I am a firm believer in women training just like men, you won't 'bulk up' unless you take anabolic steroids.
So back to basics, dead lifts, squats, leg press, and lunges.
Leg extensions are the only thing that will isolate the quads, so also fantastic, and leg curls are great for your hamstrings and I SWEAR they also work my glutes and a bit of calves as well.
I wouldn't worry too much about chest, although I would still train it a wee bit, going light, higher reps.
Keep us posted, and keep on asking if you have any questions