Day off school reason

Is celebrating a birthday a good excuse to tell my sons school for the reason he'll be off tomorrow?

He turned 4 today and goes to preschool, having a good birthday so far, but dad's working and he was only able to get tomorrow off, we have booked tickets for legoland and sea life for tomorrow and plan to take him to mcdonalds and a toy shop, so my sons basically getting a 2 day birthday. We have to call in early morning for absence but I hate faking sickness, I just can't do it incase it comes back to bite us in the arse.

So would you say I should tell the truth? Maybe I'm overthinking this and they won't care at all 🤣