There are many many primary sources available online now (Letters & Papers, various Calendars of State papers, Privy Purse Expenses etc.) so you could use those - download my primary source list at https://www.theanneboleynfiles.com/free-report/ for Anne and then see http://www.elizabethfiles.com/resources/primary-sources/ for Elizabeth. The National Archives will also give you a price for copying a document and the British Library should be able to help you too.
As far as secondary sources are concerned, always read the author's bibliography and notes and references to see what evidence/sources they have used to back up their theories. The best books are those that are fully referenced and these are brilliant for historians and researchers.