TBH experienced baby nannies (which presumably you want) aren't necessarily going to be happy about doing general housework.
Those who probably would be happy with this type of shared charge/housekeeper job are likely to be ex-Mother's Helps or newly qualified nannies who don't have the experience.
I think it's going to be crucial to be very upfront about it, say that you are a hands-on mother, the role is shared charge when you're around but you need them to be capable of prox-parenting and there's housework involved.
When you say housework, what kind of housework do you want?
The other thing to consider is cost. How much were you thinking of paying?
Hi I know that I'm being really nosey but can I please ask you what sport you compete in? Since I first read your post I've been trying to think of a sport that you can carry on with after having children and that pays women enough to employ a housekeeper. I don't want to know who you are, just what type of sport you do (I respect the anonimity that mumsnet provides)
I would echo what others have said about a nanny who will do housework. I think people tend to either like child care or cleaning but not both. ("Like" cleaning might be pushing it a bit, I know). Small children tend to be inconsistent with clean and tidy homes, IME.
The difficulty if you split the job is that people need enough money to live on, and with two jobs there might not be enough for either of them.
Could you look for a mothers' help who is happy with a reasonable amount of sole charge? This wouldn't give you qualifications though. Or a nanny with her own child looking for a school hours job?