Sounds like youre pretty much a full Celt. You might have some Roman blood from the Portegeuse, I'm not sure about their history honestly, and you likely have Germanic (anglo saxon) genes from your english side, and even on the English side it's likely your mostly Celtic.
Iberian religion is mostly a dead end, there's a few scraps and bits of info here and there but unfortunately they were all but wiped out by the Romans. I know nothing of it, all I know is that there is little to know.
So your best route would be embracing Celtic or Germanic. Understand that Asatru is a term I don't like using because it usually refers specifically to Icelandic or Nordic Paganism, when it should refer to Germanic Paganism as a whole. Nordic Paganism is just the best preserved version of Germanic myth, so most of us use that as a template of sorts when comparing it to the religions of the other Germanic tribes.
I have no connections to Scandinavia either besides the Saxon genes and a little Norwegian, I mostly focus on my continental Germanic ancestors.
I've been studying Celtic Paganism for a while now but I wouldn't call myself an expert or worshiper of it, I only know a few god-names and practices and artifacts. The main problem of Celtic Paganism is, like you said, the infestation of Wiccans and subsequently the corruptive material they put out.
I wouldn't recommend buying ANY modern books or sources on Celtic history or religion, they're no doubt tainted with either Wiccan bullshit or the general American misconceptions on the Celts (hurr durr Braveheart is so real :DDD)
But if you are truly dedicated none of that shit should matter, when you see Wiccans show them what the real Celts would have really done with them.