I have worked as a (residential) assistant under house parents (but not as a house parent), I feel I have some insight into the role. It will depend majorly on the school, especially whether it's prep, secondary or all through, and it will also depend majorly on whether you are in a dual teaching/boarding house role or boarding only.
For examples of how much it varies between schools: sometimes you are the only two looking after the house, other time you're in a team of eight or more. Sometimes you work a full teaching timetable, sometimes you have 9-5 off. Sometimes you are looking after 80 in the house. Sometimes you have a laundry service, sometime you have the help of a day matron or a gap, sometimes you ARE the laundry service. Things that might look little can be big differences!
The job is very intense during term time, remember you will most likely work weekends. You really have to love the job (obviously it's hard to know when you haven't done anything like it before!). The holidays are fantastic though, even better than most state schools. And it's very rewarding. Personally I adored working in boarding.
If you are working in a boarding house with girls your DH may have major restrictions e.g. not being around during the shower/bedtime routine! I have worked in schools where men are barred entirely from the boarding houses but obviously if you are both being hired as houseparents you would not be in one of those schools (unless you are given separate jobs- e.g. you're given the girls boarding house and him the boys!) ( I'm kidding on that last bit). You might find some of the school rules or customs around staffing sexist or outdated but as sad as it is to say, in most cases there are reasons those rules have been implemented.
The impact on your own children will vary massively with how old they are and whether they attend the school as well. You need to look into that very carefully. Does the school take day pupils? Would your children be enrolled as day pupils or boarders? If they are boarders, would they be in your boarding house? If you're looking at a prep school, what happens when your kids get to secondary school age? Will they be day pupils at a nearby school or will they board further afield?
Many of my colleagues who had kids had them boarding at other schools. You might find that a bit strange but it's something worth thinking about especially if your kids are older. Some children find school to be a breathing space away from Mum and Dad- that's a challenge if their parents live and work at school! Another was a house parent who enrolled her kids as weekly boarders, so they were in the dormitories Mon-Thurs and in her accomodation Fri-Sun!
The other thing is, if you take the role I would encourage you to keep your house if you own it. That might sound like weird/obvious advice but some people do sell up and live year round in school accomodation and then if they're not good savers they get a nasty shock at retirement age/the end of that job.
I've written a bit of an essay but I hope it helps. Feel free to message me privately if you have any questions you don't want to ask on the thread.