Maryjoa - I used to live in Marlow - have you looked at Godstowe in High Wycombe? Fantastic prep. A lot go on to (local) Wycombe Abbey from there. A bit of a further drive would be Maltman's Green in Gerrards Cross. For senior there is Piper's Corner in Great Missenden or Queen Anne's Caversham. School buses for latter 2. Going the other direction (ie Maidenhead) you have Claire's Court which is co-ed. Depends what you are looking for. Godstowe and Wycombe Abbey by far the most academic followed by Maltmans and Queen Annes. Have heard Crowne House is High Wycombe also good for prep (co-ed I think) but I don't know much about it. Of course, the grammar school (Sir William Borlase) is also fab - esp if DD loves music - would give some of the local indies a run for their money. How old is your DD?
Let's just say tutoring is paying my brother's Uni fees, we aren't allowed to call home before 7.45pm Monday-Friday and out of the question that we get a visit from my mother at Easter or the May half term
She worked out that she had at some point seen a quarter of one year at some point between Y9 and Y11.