Not quite sure if "peers of the realm" is the term I'm looking for so I'll give an example: say I would like to learn more about the lords and ladies and other notables that lived during the reign of Henry the 8th. What terms do I use to look them up online or what books do I turn to?
I've tried a variety of search terms but I'm always given a bunch of links to Game of Thrones families. Or articles about what the gentry were but not who they were. I'd love to find more pages that look like this page for the Boleyn family but any resource would do.
A lot of this depends on the level of detail you are looking for and the purpose of all of this. Peers of the realm is a good term but I would use combinations of things like: early modern era, Tudor, Renaissance, nobility, peerage, with different buzz words like lords, ladies, earl, duke, etc. A lot of results will suck but as you learn more about what you are interested in you'll get better at finding things. For example, Tudor Nobility by G W Bernard might be interesting. (http://www.worldcat.org/oclc/645819878)
If you are looking for a place to start, I suggest falling down that good wiki rabbit hole and seeing who married who to figure out the big power families of the era. For example, Anne Bolyen's sister Mary married William Carey. Their son Henry became a high ranking member in the court of his cousin, Queen Elizabeth I. Henry Carey's daughter Katherine married Charles Howard who became the first Earl of Nottingham in Queen Elizabeth's court. The Howard's are a HUGE family in this time period and a fun rabbit hole to go down. But be warned, everyone has the same name. Back to Mary, her daughter, also Catherine, married Francis Knollys. Just from this example, we have two women who were at one time called Catherine Carey. Catherine Carey Knollys was also very important in Elizabeth's court. Her daughter Lettice went on to marry Robert Dudley the first earl of Leicester. Robert Dudley in himself is super interesting but his family was another one of the dynasties. His father, John, tried to put Lady Jane Grey on the throne and was beheaded for it. Lady Jane Grey is the granddaughter of Henry VIII's sister, Mary Tudor (not the same as Queen Mary I) through her second marriage to Charles Brandon Duke of Suffolk. Charles Brandon was a big player at court although he did not come from an important family. His last marriage was to Katherine Willoughby, daughter of Maria de Salinas, a close friend to Catherine of Aragon (mother of the aforementioned Mary I). Katherine Willoughby Brandon married a second time and her son in that marriage, Peregrine, was also a player in Queen Elizabeth's court.
What I am trying to say is that everyone is related in some way and these big families keep intermarrying and pop up again and again. Last names you will see a lot of includes: Seymour, Howard, Grey, Pole (depending on how far you go back), Dudley, Sidney, Cecil, Bacon, and many more. To make things even more fun, spelling had yet to be standardized and many important people are referred to by their titles instead of their names.
Most of this info on who married who and did what is just knowledge I have collected along the way but here are some other sources. Another recommendation is to read what is cited in the bibliography. I've found a lot of good books that way. Authors will quote bits and pieces of overlapping works but often the quoted book will contain interesting things that were irrelevant to the book you read first but in the same vein of interest.
D M Loades: Henry VIII: Court Church and Conflict (http://www.worldcat.org/oclc/76852973)
Carole Rawcliffe: The Staffords: Earls of Stafford and Dukes of Buckingham, 1394-1521 (http://www.worldcat.org/oclc/2894018)
Derek Wilson: The Uncrowned Kings of England: The Black Legend of the Dudleys (http://www.worldcat.org/oclc/897025014)
I hope any of this is helpful, let me know if you have questions. I am far from an expert but I do study things like this quite intensely and can maybe point you in a good direction.