Having worked in preschool for 7 years, I'd go along with that last comment. You become very attached to the littl'uns, and when they leave you to go to "big school", it is indeed a very emotional experience for the playworkers, particularly for the little group that you have been the "keyworker" for as you've worked very closely with these individuals.
At this precise time, I wouldn't imagine too many class teachers are under strain because reports should all be written, checked and either dispatched or ready to be dispatched. The period since Whitsun though is very stressful, and I can bear witness to that. Heads will probably be under strain because they will be looking for new staff to cover any leaving at the end of this term. They will also be coping with the raft of paperwork which the DCSF insists on keep supplying, which may also impact on other senior members of staff.
Don't forget that this is also an 8 week half term and just about now, everyone is very fed up! Children at the end of KS2 are also notoriously difficult to handle at this time of year, and parents also have to be dealt with coming in to moan about this, that or the other to do with their little angel - who probably happens to be one of the worst offending children in the school. Office staff are under a great deal of pressure, preparing new registers, files etc for the new school year and fending off the parents! Just thought as well, everyone is probably very stressed at not being able to get the children outside to run some energy off because of the lousy weather we seem to have had particularly since the beginning of July!
And please get away from this idea that the teachers get 6 weeks holiday - to start with it's not a full 6 weeks unless schools have tagged on non pupil days. Staff will be in during this time preparing classrooms, labelling books, trays, equipment, taking down displays, moving paperwork on to new classes or schools and more. They will also have spent much of the last half term doing 16 hour+ days on producing reports, marking test papers as well as keeping up with the ordinary marking.
I work in a school and am chair of Governors in another school, I see the stress at first hand in both. I know Heads in the area that are - or have - taking early retirement because the stress has become too much for them to cope with - most of which is down to Ofsted and the DCSF, who seem to forget that we are dealing with children, as everything is results driven and based on numbers.
I'm not saying that jobs in schools are any more stressful or demanding than others, just trying to explain what you may be encountering and defending my colleagues who people always assume work far less than they actually do.