I am lucky enough to have a modern printing of the Anglo Saxon Chronicles. Colour Library Books of Godalming, Surrey. I see some mention that Alfred the Great had mentioned those ancient peoples. I remember the tribes that displaced these peoples as taught years ago. The Angles, Saxons and Jutes. Every English child of a bye gone era would know these names.
I watched the PBS series I Claudius. Went from him as boy under augustus t him dying as emperor. Fantastic. i think 13 hours. One of his cousins or uncle named Brittanius but not much in the series on Britian. i think Caligula went there and stepped on the beach and collected sea shells and declared a triumph for himself.
I read roman history from the founding (livy) to the year of 4 emperors, AD 69. I suggest pick a topic and immerse yourself. PBS and BBC have done some videos and Nova did some archeological stuff. Best wishes.