The Falco novels by Lindsey Davis are well written and fun, and there are plenty of them if you find that they are your thing. The BBC dramatised the first few books in the series and you can pick those up on Audible if you prefer to listen rather than read. The early books are a knowing pastiche of the Private Eye genre set in Rome in the years following the death of Nero, the series goes on to develop a life of its own but retains the crime/mystery theme. The characters travel to most parts of the Empire and the author has thoroughly researched the period and brings it to life in a very accessible way, most books have a chapter at the end where she discusses her sources and research.
The Romano-British Arthurian setting has plenty of writers putting novels in the period, not least Bernard Cornwall who published a trilogy of books about it. Also there are RPG source books for 1d100 and other systems. The difficulty is that the history and archaeology is sparse and open to many different interpretations, so don't expect one writer's take on the matter to match up with another. This can be frustrating if you want to base your campaign on more than one source. If you want to watch some actual play The DiceStormers, an Australian group of Lets Play You-Tubers, have put out a short series of VODs of a CoC game set in Northen England a the very end of the Roman period. The Vids are of good quality and the GM is an academic who has published on the period, which shows through in his love of the setting.
If you feel the need to consult an actual historian about Rome, you may want to have a look at Mary Beard's SPQR which is pretty recent (ie 2015) and has graced the best seller lists which is good evidence of how readable it is. Her book on Pompeii is also worth a look.