The Britons had already gone into the iron era which Rome was just introduced to. A disadvantage was strategy, the romans were strategically gods.
I believe the answer is:
Advantage of The Britons is that they had already gone into the iron era which Rome was just introduced to
A disadvantage for the Britons is that they are strategically inferior compared to Romans.
Being the first to get into the iron Era means that the Britons have implemented better materials into their equipment, shich give them military advantage over the Romans.
But, Julius Ceaser was regarded as a strategic genius across European continent, so he manage to outsmart the Britons regardless of their advantage.
Julius Caesar noted that the Britons had the advantage of knowledge of their terrain and iron weaponry. However, their disadvantages included a lack of military cohesion, inferior organization, and limited resources compared to the Roman legions. These factors contributed to the Romans' military success in the region.
;