Alex Kingston played Boudica to perfection in Warrior Queen (2003), a made-for-TV production. I would enjoy a full length epic sized theatrical film about Boudica, but I can't see anyone but Kingston playing the role.
Those on the list you provide are just a bunch of "flavor-of-the-week" starlets with none of the power and ability Kingston can bring to the role.
Most of my friends who have inferiority complexes are absolutely right.