It's an awful idea.
Children in Finland have ten weeks off in the summer. Finland is generally hailed as being a progressive and high achieving nation in terms of its education, as is Scandinavia in general.
Children would be exhausted, fractious and unwilling to learn. You can't MAKE exhausted, fractious children achieve by piling more on them.
I was a teacher. The first two weeks of the summer holidays I slept and got over my burnt-out tiredness. The second two weeks I enjoyed, like a normal person on their school holidays. The last two weeks I was preparing for the autumn term. That's how it generally is.
Stop talking about working parents and their lives all the time! This is about CHILDREN! Think back to your childhoods and remember those school holidays - imagine a childhood without them. Our children are going to be working until they are 70, and Gove wants them to be in school ten hours a day and not have the summer holidays we had!
If he wants to overhaul anything in the style of another country, then start formal schooling later like they do in Scandinavia and spend the first few years socialising them to enable them to become more effective learners. Stop messing with things he doesn't understand and making education more boring. And lastly, overhaul the childcare system in the UK to make it easier for parents to work so kids don't HAVE to be in school all that time. It's not a babysitting service.
If you don't want to provide for your children, don't have them.