Yeah, you can totally just use normal magic. Any knight could; as far as i remember nothing has ever kept them from learning it. You can even use your previous experience with magic as justification for why you know about it.
Alternatively, you could pick up soulfire. Yes, your magic must be used in support of your patron's wishes, and as Capital G hasn't been written up yet or a motive defined, it's really up to your GM and you. In my games, the character with soulfire couldn't heal a fey, and can't use magic in a way that would break the laws, period, or would violate someone else's (mortals only) free will.