Would you find this a red flag in a new partner?

[Cryinglightning45]

Agreed to a day trip to see some of his friends who live a couple of hours away, then he was supposed to stay at mine that night.
Very early start, the plan for the day sounded vague but I said it'd be nice to meet his friends.
I just mentioned to him "You don't think we'll be back super late in the evening do you? Just as I've got work early the next morning (start at 06:30) and might just need to get a couple of bits ready.

He looked a bit annoyed when I said that, and said 'stop worrying, I don't think we will but I don't know what the plan is' and sort of rolled his eyes.
I replied 'no worries, I'm just asking'.
I'm not trying to be a killjoy or say we must leave incredibly early, but I don't think it's a big deal for an adult to want to have a vague idea of timings especially working the next day. I didn't appreciate his response.

Fair!

He looked a bit annoyed when I said that, and said 'stop worrying, I don't think we will but I don't know what the plan is' and sort of rolled his eyes.

You are supposed to blend your life seamlessly into his so he doesn't have to consider your needs or wants hence the eyeroll. That's not a healthy relationship and if you stay you will eventually become so small you will disappear. The majority of women trapped in bad relationships will tell you this is how it starts. Get rid.

Jesus what on earth are you doing all day? This would not interest me in the slightest tbh, I would far rather mete the friends loosely for a coffee, maybe even a meal or a couple of drinks, it a whole day thats 2 hours away starting at 8:30am? I definitely would have sat that one out!

I wouldnt want to do a day trip involving 4 hours travel

The eye roll would have decided it for me.
I'd have told him to go on his own. And decide if his attitude is one I would tolerate going forward. (I wouldnt).