Boudicca seems to be almost a national hero in the UK nowadays, but did her rebellion have any real impact beyond the physical destruction it caused? Did it change the Roman administration of Southern Britain?
This is a really interesting question. I suppose to get abut answering it we need to reconcile two major facts:
After the rebellion and its aftermath, Rome ruled Britain for centuries with little internal unrest. I am reasonably confident in saying there was no unrest in the region of the Iceni afterwards.
The rebellion is mentioned in virtually every relevant source. It is a unusually well mentioned event for ancient history.
These two facts seem to contradict each other: on the one hand, Boudicca did not have any lasting impact, on the other she was noteworthy enough to be mentioned by almost everyone. I think some explanation can be found in Tacitus' "Agricola":
Rousing each other by this and like language, under the leadership of Boudicea, a woman of kingly descent (for they admit no distinction of sex in their royal successions), they all rose in arms. They fell upon our troops, which were scattered on garrison duty, stormed the forts, and burst into the colony itself, the head-quarters, as they thought, of tyranny. In their rage and their triumph, they spared no variety of a barbarian's cruelty. Had not Paullinus on hearing of the outbreak in the province rendered prompt succour, Britain would have been lost. By one successful engagement, he brought it back to its former obedience, though many, troubled by the conscious guilt of rebellion and by particular dread of the legate, still clung to their arms. Excellent as he was in other respects, his policy to the conquered was arrogant, and exhibited the cruelty of one who was avenging private wrongs. Accordingly Petronius Turpilianus was sent out to initiate a milder rule. A stranger to the enemy's misdeeds and so more accessible to their penitence, he put an end to old troubles, and, attempting nothing more, handed the province over to Trebellius Maximus. Trebellius, who was somewhat indolent, and never ventured on a campaign, controlled the province by a certain courtesy in his administration.
To put this simply, Boudicca did not initiate any long term prospect of independence, nor was her cause in any respect carried on by later leaders. However, the rebellion and its aftermath did prompt the Roman administration to act with a lighter hand towards the Britons.