MCS will be taking girls for the first time in 2027 and into both years 3 and 4 (J1 and J2). So if DD1 is currently in year 2, you could just send all four of them there… (eyes water at the thought of the fees…) Before then, I would send them to one of the many decent but not brilliant state schools. Christ Church is not, imo, a good school and the only people I know with children there haven’t been able to get places elsewhere. If it has to be private, I would pick the Dragon over Headington Rye but not with a great deal of enthusiasm.
We have two DS at MCS and are very, very happy with it. I don’t find it a pushy school at all — in fact, it’s very relaxed in many ways. But I wouldn’t recommend it for a child who was only just scraping through the test. If your DDs are extremely bright, I think it would be an excellent choice.
Even very short commutes in Oxford are a nightmare. My kids take the school bus even though we live only a mile and a half away, because we both work in London. It works very well. Picks them up at five to 8 about 2 mins walk from our house, and then brings them back for half four. Lots of second formers take the bus and would likely be a good choice for DS1 from September. (Mine have actually made some good friends, despite the fact that it’s only a ten minute journey!)
Does Bruern Abbey have a bus? If not, that will be an unbelievable nightmare from anywhere inside Oxford. The congestion charge means that there is (ironically) almost constant congestion and stationary traffic on both Woodstock and Banbury Roads during school commuting times.
Do either of you need to go to London? If so, I would look at Walton Manor rather than the (dull, amenity-less) area around the Dragon. Much closer to the station and a nicer walk/cycle ride, and great having the Jericho restaurants, cinema etc. With four children you might struggle to find a big enough house, but there are good-sized (3000 sq ft+) houses on Warnborough, Leckford, Farndon etc. roads.
One tip: people in Oxford like to put their houses on the market in the spring. Your best bet is to start looking now. Most of the good ones will be gone by May, and it can be hard to get an offer accepted.