Hi Michiel
If you haven't got it already, I'd recommend you get AVS Tree Frogs as it is a great read. Note that in the book it says Whites can be kept without any lighting (UVB), however since then the author has suggest that they UVB is the best source of D3.
It will take a while for a roach colony to be established enough to feed out to hungry whites but otherwise easy to set up. Roaches do best at warm temperatures and with humidity for breeding, however I have found a large roach in my house months after feeding my toad one, so they're pretty hardy. You can keep them in plastic rubs, with a heat mat on the bottom connected to a thermostat, moist coir or moss substrate and some cardboard egg crates, food etc. Crickets are my favourite source of food and will die quite quickly if they don't have access to food, water or moderately warm temperatures.