I'd buy a set of PPL books, it's cheaper as a job lot. Any of them are fine, it's a matter of personal taste. I used the Jeremey Pratt (AFE) set (as per link), they were fine, I still read them now and again to ensure my knowledge doesn't wane. I found the AFE set straightforward and fairly free of unecessary crap/jargon but others opinions may differ.
There's the AFE set, there's Trevor Thom's set and the 'Airpilot' series, they all have the same info so go to a pilot shop and have a flick through to see which style you like the best. I've looked at Thom's books and like them, some say they are too 'Techy', I don't agree (I've got his book 5 - The RNAV/IMC one and think it is very good), like I say, it's a matter of personal taste. I'd also buy a current exam 'Confuser' book too, well worth the money!!
In addition to Amazon, ebay is worth a look, they often have whole PPL 'kits' (all books & may incl. plotters, pens whizwheel, bag etc.) up for sale from people who have started and given up or intended to & never did start. You'll save a packet, just make sure the books are current editions (esp. AirLaw) or aren't older than the previous current edition.
The other book that's worth reading is the famous "Stick & Rudder" by Wolfgang Langewiesche, an excellent book, even though I only read it after qualifying!!