Don't you think 5 days a week is too much??

My son has been going nursery since he was 2 years old, only 2 and a half days a week which works out 15 hours in total.

His 4 now and in just over a week he starts school, the same school he went to nursery at so I'm not worried too much because his friends will be there and his been introduced to his new teacher and classroom a couple times during his last nursery year to help the transition but difference is that its 5 days a week, 30 hours! I'm hardly going to see my baby, his baby brother will be home with me and I'm worried he will miss him, theyre literally best friends and the thought of going to playgroups to keep baby busy is making me feel guilty that my boy should be with us too!

I've been a stay at home mom since my oldest was born, this will be really hard for me plus I hated school and saw it as a prison so that's probably not helping, I hope he enjoys it there ☹️

Edit- sorry I'm in the UK, his going into reception class, turning 5 in this academic year and this class is compulsory to be in full time which is 9am-3pm, we don't start the day at 8am here. I can't exactly pull him out of school unless I want social services to be knocking on my door so this is more of a vent that I think its too much, me and my partner have discussed homeschooling its not an option right now