It's always the patriarchal conquerors like the Ancient Romans or the Ancient Greeks that they idolize and never the people like, say, the Picts or the Celts or the Gaul that rebelled against the brutal Roman empire. It's never the Scottish or the Irish heroes who fought back against the British Empire that followed in Rome's footsteps. None of them probably even know who Boudica is.
Ironically, a lot of the stuff you could call "white culture" was burnt at the stake, banned, brutalized, and literally demonized by the Empires that chuds think are so civilized. A lot of pagan culture was lost to time, or warped by Roman 'scholars' for propaganda purposes. If they truly cared about their 'culture', then "Muh Christian trad wife' would be seen as killing the identity of pagan women, rather than an aspiration.
Boudica entirely makes sense as a British nationalist symbol a very old idea in British politics from the break from Rome and becoming protestant to brexit is that as we aren't on the continent we will never be respected in continental Europe and as such being part of any collective European identity means foreign rule. It's a strong throughline in ideas about the Norman Yoke, Roman Catholic clerical authority being resented, the English civil war and now the EU
Boudica being anti-Roman fits neatly into the political ideology of British meaning not European