So true, the ebooks free on MobileRead
https://www.mobileread.com/forums/forumdisplay.php?f=126 are great and you can just drag and drop them to your 300. You can also use the epubs on MobileRead as well. Plus Kobo
http://www.kobobooks.com/ as well as most other sites have free books as well. Not only classics but contemporary independent authors as well. Do be aware that to read the free books from Kobo (and some others) you do need Adobe Digital Editions installed on your computer.
Concerning a light, this is my post from another thread about lighting......Your options would be perhaps different in the UK, but treat it like you are buying a light for an old school paper book and you will be fine....
I picked up a "Pathway lights: Multi-pose Brightbook" at Target. I notice it is not available at the Target site, but only at the stores in the book department. It has 4 leds, two light levels and was only $8.99. It clips on the case with ease, but would not be able to clip on the 300 itself. It works perfect. The low setting is all I need, and it is twice as bright as the high setting on the Sony one. I use rechargeable AAA batts in it....