We did it throughout my school career - a week next to October half-term, and a week next to the May half-term. We couldn't go in summer, because it was harvest, and if we didn't sometimes take picnics up to the harvest field, we hardly saw Dad at all - and so Mum insisted we went away from the farm, as a family, so Dad got a proper break.
We spent holidays doing things like going round museums and looking at geology, and I used to read stuff like extracts from the Royal Commission which lead to the 1842 Mines Act, and stuff about the Chartists and the Newport Rising and so on (South Wales autumn holidays, all that,), so I really don't think my education suffered, other than my holidays did influence the path I later took (a history degree, with a dissertation on the history of coal mining.) We did any extra homework we were given, and I spent a lot of the rest of my spare time reading and writing stories anyway. Plus once I was in the 6th form, I arranged to stay with a friend for the school week, and got the train back home to stay with them after the half-term week, because I didn't want to miss any school. (I may not have been very typical...)
My parents requested it every time (I remember having to ask for the forms from the school secretary), and it was never refused. I don't know if that would have been different if I hadn't been near the top of the class most of the time, and otherwise, I had a very good attendance record - just 3 days sickness for my entire school career.