Uvb--get a linear bulb for him--the tightly wooven screen and that style of bulb barely allow them to get any uvb.
(I just switched as well after one of the chain pet stores sold me a very similiar set up and our Cham kept getting sick.)
The plants will need a plant light also--i just asked a bunch of ?s myself about these as well and was told the Jungledawn megaspot bulb was excellent, but pricey, but that a 5500k-6500k would be a great linear ho bulb for the plants to flourish and keep my lil guy healthy and happy.
Good luck, it's a very quick leaning curve unfortunately, but I cannot imagine a better spot to be in for that honestly. I just disregard anything the chain stores tell me now....really. Everything is marked up, none of the animals are housed properly at our particular Petco chain, and they had me so misinformed, I feel lucky my lil guy is still active and recovering from it all.
It would be a good idea to get a fecal test done on your new little guy, esp if you have other lizards about the house to make sure he is parasite free. Not at the pet store you got him from, they don't typically see an exotic vet at all, at least at ours their "health warranty" means they'll give you a new one when they don't treat the sick one -_-.