In the past, parents have asked previous Y6 teachers which KS2 SATs revision guides we recommend. I have added a link below to the Achieve: The Expected Standard books (written by Rising Stars) range that we have used before. They are good but other companies (such as CGP) produce similar things and it really does matter which one your child prefers. Most pupils should aim for the Achieve: The Expected Standard in maths, reading and grammar and punctuation. Again, other companies offer similar products. Some pupils may need to alternative books (the Achieve range are entitled Achieve: The Higher Score). Please check with me which you need before buying.
Please don't let your child start revising too early. They should be like finely tuned athletes who peak at just the right time.
Achieve Range Samples Here