Doing Time by Jodi Taylor is the 13th instalment in The Chronicles of St Marys series (the SMSA library has them all).
If your taste runs to madcap historians running up and down the Timeline, with more than a healthy dash of Time Team and Monty Python histrionics thrown in, this series is the right one for you!
Doing Time has moved forward a few years (if that is possible) from the events of the 10th book (the 11th and 12th are short story collections which fill in some big gaps) and focuses on Matthew, son of Max and Leon Farrell, who has chosen to join the Time Police. He and his young colleagues are possibly the worst batch of new recruits taken into the Time Police in living memory but, due to his gifts, is accepted before Anything Else Can Go Wrong.
This series is catalogued as science fiction (due to the time-travelling aspect) but also delivers a healthy dose of prehistoric and ancient history adventures (due to the time-travelling aspect). The author is British and the sheer craziness of the St Marys adventures is very similar to the works of Sir Terry Pratchett’s Discworld and the aforementioned Monty Python skits. Highly recommended for those who don’t take their SF too seriously (or need a physics degree to read it).