Bodybuilders and the uninformed will immediately insist there's no point to cardio and lifting, blah blah blah.
Bottom line is, for you initially your goals will be like many who start the gym.
I want to loose weight.
I want to be fitter.
I want to look better with my kit off.
Nowt wrong with this. Go to your gym, you'll be specced a basic routine for four weeks that will consist of a warm up, CV session and MSE (muscular strength and endurance session) that will build a base level of fitness and achieve the changes you're looking for.
Yes, swimming is excellent. Post-exercise it can help reduce lactic acid and increase/maintain flexibility.
Experienced vets, budding enthusiasts and know-it-alls will try and ply you with a wealth of information. Forgetting that initially, you need to accustom your body to exercise, and your mind to going to the gym regularly.
Your main focus should be this:
-Whatever you do in a session. Intensity is your key goal. Do it hard.
-Take a look at your diet, don't worry too much about it, but start cutting out crap, and calories through liquid.
-Get into the habbit of regularly getting to the gym, working hard, and enjoying it.
Too many vets forget what its like when you first start out, and are so eager to pump you full of the knowledge its taken them years to gain that they put you right off exercise
For the first 6-12 weeks (usually around 8) your body will adapt slowly, you'll gain lean mass and loose body fat. When you've been at it for 2-3 months, and the basic stuff isnt cutting it, that's when you start getting more serious.
Good luck,
Ant
EDIT: Muscle Tone is defined in the industry as the quantity/size of muscle fibres recruited at any given time to maintain posture and stability.