If I was keeping my horse at your yard in full livery, then I would expect that to be over the weekends too. However, if you had said when I came onto the yard that it was only full livery Mon - Friday, I would respect that, so you are not being unreasonable, but it may not stop me, if I was in a rush/short of time, asking one of the grooms on the off chance they could help out - but I would expect them probably to say no!!!
However, I would want access to my horse after 5pm - or when you are not around if I was paying full livery prices.
I completely understand you want to keep the 'school' part separate and wouldn't want to enter that area, nor should I need to. But, I wouldn't ask/expect my horse to be in that area anyway. If you have clients with horses in that area, then they have to abide by the rules that if you are not there then no access, but why would anyone want their horse in the school area, rather than the livery area if they couldn't get to it?
Our yard is a DIY yard, but everyone has to be done and off by 9pm, when the automatic gates shut - unless a horse is sick, or they have pre-arranged for a reason. Gates don't open until 6am (unless previously arranged for a show etc.). Thankfully this means we don't get woken up by cars coming into the yard and horses clopping beside the wall on the way to the field! I just need to educate them on not banging the fork on the wheelbarrow every time
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