First of all congratulations to any parents (and their wards) who are in a position to select between all the fantastic schools we are so lucky to have in our county!
I think there are quite a few boys going from Watford (and surrounding areas) to QEB. We are in north Watford and been car-pooling for 2 years now.
The journey isn't too bad ~35mins door to door - or lesser if taking the M25. It actually takes me less time to reach QE than it does to reach WGSB during peak times
, Of course if you are living south of Watford then things might be different.. but I do suggest having a drive on the Rickmansworth road (and also your QE route too) during school times to check it for yourself.