From the OP I kind of took it as the trainee has announced 'I can only do x hours' as a that's it sort of thing.
She came in and said off the bat that she could only do 8.30-3.30 and I asked if there would be any chance of that changing.
A good teacher is going to probe and see what more can be learned and what more can be done to achieve the end both the teacher and trainee have in mind.
The OP wants to move the fixed object here - she knows it's childcare, and must have some appreciation of what ILoveDolly understands; it is easier to organise childcare when you have fixed hours and the increased income that comes with a full time professional position.
Instead, why not think a little (it's actually not that much) out of the box and consider email or a phone call at a mutually agreed time later on, perhaps when the small children of the trainee are in bed and the OP will have settled her own family for the night too.
yet you knowingly signed up to a course where your placement schools could be anywhere in the region, some could start earlier / finish later, you'd have twilights and meetings etc. Either you really are silly or it's not set in stone and you are very naive if you think that will get you far
This issue effectively keeps mothers of young families who are not well off out of teaching. It is discriminatory to expect such extreme flexibility on the part of the trainees, most of whom are women, and tutting at someone who finds herself between a rock and a hard place is unfair. They have a desire to provide better for their families, they have a desire to do this by teaching, which is not an easy path to a secure income, and they find massive hurdles placed in front of them, and the way they deal with those hurdles used as a means of judging their personalities and even their suitability for teaching.
The problem is the lack of flexibility and the lack of acknowledgement that young women sometimes have babies and young children to take into account. It's the not really very new problem that workplaces fail to account for the fact that men and women have lives. They can get away with that to a large extent when the trainees and employees are men who have 'secretaries, kid taxi-services, childminders, laundresses, cooks, and PAs' - aka partners - at home dealing with the details of their lives for them, but it all comes apart when the trainee or employee is a single mother or someone whose partner cannot do the childcare element of family reality.
Are women really naive to expect that in a profession that is dominated by women, the reality of women's lives would be taken into account?