Some incredibly harsh responses here! The OP has not said how old her children are or what they are doing this afternoon. It could be something that had to be booked ages in advance and/or extremely expensive and/or involving other people. I can just imagine the AIBUs from the others affected if OP did drop everything to apply for this job (with no guarantee whatsoever she's going to get anywhere with it)
AIBU to be pissed off with my friend who's just messaged to say 'Sorry, can't go with you as planned today, can you manage all the kids on your own? I've just seen a job vacancy I want to apply for and I have to get it in by 6pm.' We arranged this after Christmas and it's cost us a small fortune to book all the tickets. No, I can't manage six kids on my own! They won't even fit safely in my car ...
AIBU to be fuming because my SIL has pulled out of bringing the kids to see my PIL who is just out of hospital so that she can apply for a job she's only just seen?
AIBU to be really upset because my DP isn't coming on a long walk we've planned with the kids and the dogs because she wants to apply for a job that frankly she stands no chance of getting? It's the only day we're both off and we've all been looking forward to it for ages ...
The issue here is that the job is only open for applications for four days over a period where a lot of staff are on annual leave, and those staff are disproportionately going to be women of childbearing age. This is obvious discrimination. It's inconceivable that the department manager was unaware that so many staff would be off during the period this job is open for applications. The way this has been done absolutely stinks.
I applied several times during my working life for jobs which it then emerged were basically always going to go to someone else, for various reasons. It's extremely demotivating. If I had my time over again, I'd have moved employers to a place where staff were treated with more dignity and respect.