Advice on flying on a codeshare flight (VS7808) operated by

I will be flying on VS7808 (LHR-HND) operated by ANA, next Wednesday.
This will be the first time that I will fly on a codeshare flight. I would like to know if I would be able to choose my seat on the VS website or would I need to contact ANA?
If there are any other further advices, all will be gratefully helpful.
This will be the first time that I will fly on a codeshare flight. I would like to know if I would be able to choose my seat on the VS website or would I need to contact ANA?
If there are any other further advices, all will be gratefully helpful.