Do you know the coach services from Beaconsfield grammar towards Slough?
I can't find the info anywhere.

Looking On google maps there's apparently a bus from Slough to the school. You would have to look at the timetable to see if it suits. Overall journey would be about 50mins though. (Note it might be worth looking at the allocations given the distance to check it's a viable option. I don't know from memory.)

You are also looking at Burnham? I think thats a better journey form memory.

Have a look at google maps, it is useful at giving a guide to journeys and possible public transport options.

You can also put your starting point into the Bucks County Council home to school transport pages but you would have to put Burnham as a starting point as BCC have no obligation to run school coaches from out of county. I would think that Burnham Grammar or the Slough grammars would be a better bet as the buses could be quite slow in rush hour (from memory I think it's the 74, but check on Google maps).

In recent 5 or 6 years the cachement for Becky High has been too tight for a place from Slough to be granted, Burnham Grammar is usually the only in distance option... last year there were spaces given out to Slough children but this may turn out to be a one-year anomoly ie next year the out of cachement distance will shorten again.
Look at the admission tables at the top of the Bucks section, and put yourself into Google maps to find out how far you are from the school.

That aside, it's a heck of a drive to do each day if you can't get a public transport option.
I believe there is a private coach or you could drive north to Burnham or Iver and ask for a place on a Bucks coach, but that is only given out if there's spare space once all the Bucks children have been booked in, and it rules out any afterschool activities.

A friend's daughter goes on the public bus. She has found it quite a slog over the years and is planning to go to a nearer 6th form.

I don't know why you are particularly interested in BHS but I'd look at the excellent schools you have in Slough and consider the whole picture including all the time, hassle and money involved in attending a school so far away especially if your child wants to participate fully in school life (after-school clubs etc)

Obviously the interested starts when she didn't pass the Berkshire 11 plus

Is wycombe high better or beaconsfield?

Are you not going to consider wycombe high?

Depends what you mean by "better". Which did you prefer when you visited? Are there any particular subjects or sports, for example, that you're looking for?

I liked BC more than WH. On terms of Eu keys more interested in science and maths.