Also, as capers mentions above, there is the route into Stroud, then over to Glos.
You'd need to be in Stroud to catch the 7.40 (no. 93) which arrives at St Barnabas Church at 8.10. The next bus at 8.10 won't get there until 8.36 and then you still have to get to school. I think the school day begins at 8.35 at Ribston?? On the return journey there's a bus at 15.08, though I suspect this will be too early. The next one is at 16.18 getting into Stroud at 16.45.
There is a bus from Stonehouse to Stroud, picking up in Stonehouse around 7.05/7.10.
All the buses I have mentioned are run by Stagecoach.
You'd need to check all your times from getting to bus and in/out of school.
That's presuming there won't be any changes before September!
These might give you more detailshttp://community.stroud.gov.uk/_documen ... etable.pdfhttp://ww5.gloucestershire.gov.uk/Busti ... 093MF.HTMLhttp://www.stagecoachbus.com/GetUpload.ashx?Id=2006