Your coin is a "Late Roman Bronze", in the name of emperor Honorius, who ruled the western half of the Empire from 393-423 AD. The obverse legend reads "DN HONORIVS PF AVG". The reverse shows two Roman soldiers and the legend "GLORIA ROMANORVM". Unfortunately, the coin cannot be fully attributed to mint, as the mintmark is in the area beneath the soldiers feet, which is missing from your coin.
Honorius was the "last Roman emperor of Britain" - it was he who ordered the withdrawal of the legions from the province. Roman coins of emperors after Honorius are much scarcer in Britain.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis