So my gyms opening time is actually 6.30am, only giving me about 1 hour 15 mins in there.

Being as i want to lose weight, would it be worth me doing only cardio ? or is doing weights as well a better alternative? (i want to get back on the weights for some definition) i will be going every week day morning, so can alternate between weights and cardio (have read that doing both in the same session is pointless?) will be adding swimming to the list too in the not too distant future !