Firstly, the rule in England is now 6, the family will be 7, so you cant go anyway.
Secondly, Your DD is being unreasonable to expect you to take time off to go and stay with her, unless she cleared it and arranged with you before she got pregnant that you would take time off? No, didn’t think so.
So, No you aren’t being unreasonable, but a chat, preferably face to face might be a good idea to prevent this from escalating and ending badly for your relationship with your DD and her family.
Army horses loose on London streets