If you want to learn about accounting from fundamentals up, I recommend Frank Wood's Business Accounting 1: http://www.amazon.co.uk/gp/aw/d/0273712128?pc_redir=13981155...

For more advanced topics, the 3rd party study guides for the major accounting qualifications are pretty good. Try searching Amazon for 'BPP CIMA'.

Note: these are resources focused on accounting. If you are interested in finance, then you could do worse than starting with Brealey & Myers: http://www.amazon.co.uk/dp/B00DDML9U2