The date is 2017 and 2018 of the Britannian calendar. If they date from the birth of Christ this could be 2017 and 2018 AD, but their chronologists might have selected a different year for the birth of Christ than ours did. I read some where that the Britons selected a high king after defeating a Roman invasion in the alternate history of their world. That could have been the first year of the Britannian calendar.
If that was one of Caesar's invasions in 55 or 54 BC, 2017 be about 1962 or 1963 and 2018 would be about 1963 or 1964 AD. If that was the invasion of Claudius in 43 AD, 2017 would be about 2060 and 2018 would be about 2061.
Of course the first year of the Britannian calendar might haave been at some other moment in history.