Threadmill

Hi everyone was just wondering if I should buy a treadmill, so I can exercise, to hurry this weight loss. As some of yeah no my son has special needs ,so I don't have time to go to the gym , plus the fact that I would feel very conscious surrounded by skinny people. I find my weigh loss has slowed down a bit and I have been doing lunges squats etc . I got a gift of the zumba DVD for Christmas .my question is would you get a better workout on the treadmill versus the zumba
Thanks in advance for any replies
Tigger x