LOL tuck shop arms LOL.
I would suggest to keep your cardio/swimming routine and add in 3 days of medium weights.
Start off light, ie. Start with 30kg on bench, yes, might feel REALLY light, but, if you go heavy, you WILL tear muscles and you will be out fo action for a week or two.
Do that for a week. Add a bit more weight ie, to 40kg, do that for a week. if that is to light, add another 10kg and so on.. You want to get say 3 sets of 10 - 15 on those weights.
If you were bulking. then i would say 3 sets of 6 - 8.
Curls, start on say 6kg an arm, go to 7.5 and so forth so you get to a point where on your third set you are REALLY feeling the pump (Skin tight across your muscles) heading towards the 10.
What gym do you plan on joining and are you going with friends or yourself? If i were to recommend a gym, i wouldnt recommend a boutique gym ie, fitness first, equilibrium etc. You want to train, you train with like minded people, Nitro gym is great, maxs in dandenong etc.