So, the Romans didn't slaughter "civilians" in their land-grab in Britain? I'd hardly call her force of troops thugs.
Patriots was more like it. The Romans were the thugs here.
And regardless of the outcome of that battle, the odds were stacked against the Britons. Eventually the Romans would have triumphed due to better training, logistics, strategy and numbers.
But she gave it a good try.
If she would have undertaken a guerrilla war, a la Caratacus, I might agree with you, especially considering the Iceni's homecountry had a lot of fen. But she didn't. And she didn't really go looking for the Roman Army, either.
The IXth [or a part of it] ran into her [Point, flank and recon were always a Roman weakness]. Bouddica seems to have no interest in anything but looting [Yes, the Romans did kill lots of civilians, but not usually if they surrendered in a timely fashion]. And when the Roman Army found her, and withdrew, she launched one of the dumbest assaults in military history.
The Romans were heavily engaged at Mona when she startted her revolt. Instead of attacking their Army in detail [IXth first, possibly IInd Augusta second], cutting off the ports the Romans depended on for supply and reinforcement and then either ambushing them, or defending the field of her choice; or starting a guerrilla campaign of harassing attacks, she lost it all on one throw [or her troops did; she took off]. Good try? Not even close.