I’m sorry that you are feeling rotten op 💐
It’s especially awful when your dh is away and you are in charge of dc. That is the worst bit of parenting I think. Also when they are ill and you are on your own.
Sounds like you have a virus and you need to rest as much as possible but keep taking little sips of flat lemonade every 15 mins to keep hydrated. Or buy some sachets from the chemist and ask their advice. Or get something delivered by an on-line chemist.
Do you have the name of a friendly parent in one of your dc’s classes who would drop your children back home for you? If you don’t, this is the catalyst you need to get a small group of friendly parents together who can help one another out in a crisis situation. Everyone needs help occasionally!
Once home, it’s survival time. Ping microwave food and you can all sit in front of telly while you rest.
Do you need to ring your doctor to get a sickness certificate for work? Everyone gets ill occasionally and as long as you are not off sick regularly for no good reason, then your work should be understanding about you having a couple of days off to recover from a viral illness which is what this sounds like. It hardly helps them if you spread this illness around your workplace.
If in doubt, look up NHS guidelines or ring 111 for advice.
I hope you feel much better soon and rest as much as you can while the dc are in class.