I would suggest that you get a part time job in a hotel or cafe or gastro pub first - then you will have some idea of working from the other side of the counter.
It is great that you are great cookers, but aside from the administration of the money side of the business there is a lot of other things going on in a cafe, pub or restaurant.
Knowing how staff work, knowing not to employ to many staff (which is often a great down fall of a business) and working out how you plan to ruin things.
If you think keeping your own jobs and working part time is to much - then think again about the long hours you will need to put into your own place.
For the first two years you will be looking to break even, don't really think about any type of profit until after three or four years.
When you want to open up a food business think about the regulation of how many covers you will be able to have in the building you get - then think about the regulation that the council will allow you to get and then think about what you will do when the council change there minds over the number of covers and reduce that number - yes it does happen 
All staff needing food and hygien certificates, this is a requirement and if staff turnover is high it is going to cost each time you employ ( I know soem places just give a quick guide and get t it done online for a small fee to cover themselves - other I know just sail by the wind and chance it) - enviromental visits to check everything - will you know what they would be checking and how to set it up like that in the first place? Food probes, tempertures of friedge etc and keeping charts.
I am not trying to put you off - but as the post above says food is a failure business for a reason and you need to think about the above and then much much more that I can't cover on here right now.
I love hospitality it is great - but it is very long days and hard work. You will be chef, administrator, cleaner, waitress, kitchen porter and receptionist for quite a few hours of the day 