1) CGP has two types of workbooks, normal workbooks and test practice workbooks. They say they have updated them for 2014 curriculum but I haven't used them yet so can't comment.https://www.cgpbooks.co.uk/Parent/books_ks3_maths_workbooks
They also do a range of textbooks that have many practice examples. But again I haven't used them.
2) Letts do some books but I haven't used them either.
3) Galore park, I read that the 13+ scholarship level covers most of Ks3 (or even more?). There is a text book series and then there is the revision book. For textbook series you have to buy answer book separately which costs ££££s. But the revision book seems good. Again I haven't used it just saw the sample pages and contents on their website. They also do a mixed practice exercises book which has answers in it. And then there is the Maths Practice Exercises book but it has separate answer book.https://www.galorepark.co.uk/Mathematics#&pid=4&l=143&c=&se=&limit=true&type=1
4) Some other publications I read of are SMP, Nelson Thornes and Collins(year wise workbook). Again, haven't used them so can't recommend any.