Here are simple links that will take you directly to past paper resources from a variety of sources for a variety of needs.
If you have not used this site before then this will be a good find for you. The KESH GCSE separated past papers are a fantastic!
Click the image above and take a look.
Answers can be found here: http://www.thelifecloud.net/schools/CongletonHighSchool/spaces/Maths/resources/Pages/KS4TopicBasedQuestions.page
A lot go people know of this sites author, Craig Barton. This is a great page on the mrbartonmaths site which will save you a lot of time. This page gives exams, mark schemes, full written solutions and video solutions. It also gives links to video tutorials on youtube, downloadable revision guides and basically anything that any learner could ever want, ever.
These are SAT separated past papers with answers for revision of topics.
The famous emaths. If you click on the link it will take you to the emaths SAT papers. KS3 maths sats papers from every year with audio and mark schemes. Fantastic work from a fantastic site.