Hello Betty (great name!) and Incaminka...
Betty you can make it more tough by using heavier weights to work harder, and even adding weights to some of the cardio sections (she does that in L3). If you don't feel any affects, you could move up from L1 quicker. I'm sure you'll still get benefits from it though.
What's pole fitness btw? I'm intrigued!
Incaminka you'll need a mat and some handweights. You can start with bottles of water / tins of beans or something, but you should get some handweights to get the most benefit. I'd look at 1 or 1.5 kg to start with, but if you can buy a set (say 1 to 3 kg), go for those as you'll surprise yourself with how quickly you improve and get fitter! Think amazon or argos sells sets of handweights for a reasonable price...
You'll be fine doing the Shred though. Jillian M says on the DVD that she has 400 pound people doing Shred type stuff so there's no reason for anyone not to do it. Also, if you are finding it hard, it's never very long before she moves on to something different, and it's all over in 20 mins 
Right, have done my requisite amount of dithering and am off to do something now, dare I say BFBM again! I'm hooked I tell you 