As above, the question is very unclear; where did the Romans first invade what ? They invaded many countries.
Britain had a Roman incursion in 55BC by Julius Caesar, and a larger incursion the following year by this same magnificent general, but these were not invasions
meant to occupy the land.
The real invasion of Britain on a full scale came in AD43
under the emperor Claudius, with 4 generals commanding the 4 legions, the 2nd. Augusta, 14th. Gemina, 20th. Valeria Victrix and the 9th. Hispana.
Richborough, on the coast of Kent was in all probability
the landing-ground for this invasion, with possibly a cohort or two coming ashore at Chichester.