I find bodycombat is good for a cardio workout, though it will do some toning too. There are squats and lunges etc and I find it gives my shoulders a good workout too as they usually ache the next day!
Bodypump is better for the toning side of things, it's a good all over toning class. You use relatively light weights because you are doing a lot of reps. Give it a try and use the lightest weights for the 1st class or 2 while you get the hang of the technique. It's better to do the exercises with light weights and good form than to use weights that are too heavy and do the exercises incorrectly - you won't be targeting the muscles in the correct way and may risk injuring yourself. Within a few classes you should find you can up the weights a bit.