Hmm, Blaca, I think is from the Old English 'blaca' which meant 'dark, black" and usually denoted someone with dark hair or a swarthy complexion. The surname Blake
arises from this nickname.
Cod is a little more difficult, do you mean Codde which is found in place names as an Old English name but is unrecorded elsewhere. In which case it may be mean "bag, pouch" from the Old English cod(d). It could have some ties to the Old Norse 'koddi' meaning "pillow" which is probably itself related to the Old English cod(d) anyway but to be honest I'm just guessing as there isn't much information on the name.
I hope this is of some use. :)