The shots from King Arthur look very promising, apart from that unfortunate strappy outfit (could she really draw a bow in that without it falling off?), and made me immediately think of the excellent Rosemary Sutcliffe novel Sword at Sunset, which is an Arthur story based (I think) on the earliest, Welsh Arthurian stories, with a Romanized Celtic Arthur fighting the Saxons. It's probably out of print now, but well worth reading if you can lay your hands on it. Most of RS's stuff is, especially the Lantern-Bearers series, set in late-Roman Britain, which run on into Sword at Sunset, and Mark of the Horselord, which is basically a Romano-Celtic take on the Prisoner of Zenda.

I read as much of her stuff as I could lay my hands on in my teens.
Sword at Sunset also had the excellent effect of inoculating me against Mists of Avalon, which I managed about two chapters of before hurling it aside with some force.