If you can stop at AD14 that would be nice. Unfortunately all the British provinces go past AD14 as there is no history for Britain, except for Caesar's two invasions of the south east and the fragments of information which exist from Pytheas and Poseidonius. So ideally stop at AD14, if you have to (as I did) go a little further into the 1st century AD, but don't go into the 2nd century AD.

ALso, in the people, culture, society part, feel free to begin before 272BC if the archaeological evidence allows it, just don't become too excessive