Same, I would suggest you do all the past paper's, they're the best way to revise . Apart from that it's just making notes from the book, unfortunatley there aren't many decent resources for Physics B as there are so few of us who do it! If you have any weaknesses start there, don't revise bits that you already are confident about, it's just a waste of time.
Finally just did unit 5 exam today :D ^^^ true not many resources you can find online for this spec also the book is terrible but yh just do all the past papers and as many qs as you can from the book. i personally prefer unit 5 than unit 4 its much shorter chapter