Those fluorescent tube kits seems a bit dopey to me for this, not efficient enough.
On the cheap you could use this – the second one the Solar NiCd charger as a starting point for the power capture/storage. Mount them RIGHT under a skylight.
I have 2, they’ve lasted 3 years and I’ve currently hacked the 2 panels into a USB charger. There’s a small socket on the side, pop a wire into that. Add a switch, and some batteries [decent quality C-cells will fit] and then head over to
http://www.candlepowerforums.com/vb/forum.php?
To find a simple “Buck” [voltage dropping] regulator.
I’d try it with a pair of 1W 4000k [natural white colour] LED’s. They will need a heatsink about the size of a matchbox each, maybe less.
I reckon the whole lot will cost you less than the £50 for the cheapest kit you linked to, let you learn more and you get a pair of great portable solar battery chargers you can unhook and use camping/touring [As I did, all the gear I took on my trip used AA or AAA batteries and they were kept topped by sitting these chargers on the top of the panniers 🙂 ]