I had a c-section OP. It was also an emergency. To me, the c-section tells a big part of your story but not all of it.
You have a newborn baby who is 3 weeks old. 21 days. Your baby is so tiny and new, and you (as parentS) are still trying to establish a "newborn normal" (not a routine). You're still trying to work it all out in-between cluster feeds and and sleep.
I think it's very reasonable to say "We're establishing our new life with baby and a weekend away in a new environment and away from home comforts is not something we are prioritised with right now."
I think it is also very reasonable of you to be asking your husband to stay home and do this with you. I don't know what his paternity leave is but I look at it like this: paternity leave is woefully short as it is, if he is still on paternity leave then there's a reason for it and even if he wasn't- it's the weekend! A weekend where you've looked after your baby all week and now it's time to establish family time with your new baby who is not even a month old.
Now- let's address the fact that you've had major abdominal surgery. If this was any other surgery (not a c-section), you'd be expected to rest. In fact, my bet is that there would be people who were wanting to help you more with baby but somehow because it was a way of delivering baby it's all considered appropriate to not help.
I read a reply where you were asking for clarification on custody and this absolutely breaks my heart for you. It shouldn't even be anything you feel you need to think about and I really hope your husband shut his mother down during that conversation.
Personally, I'm disappointed that it wasn't an instant "I'm in the wrong place and need to get home to my wife and child," which was then acted on.
I also read a response where someone had said that they had a relative who made a long journey 2 weeks after baby was born: and I wanted to reiterate to you that just because that family chose to travel with a tiny newborn baby; and it was right for them- it doesn't mean it has to be right for you and your family. In hindsight, that particular family may look at their travelling and say they'd do it differently given the chance. They may say it was amazing, but they aren't you. You have made a decision that should be respected and listened to.
I can totally appreciate how you may be feeling, OP and am so sorry that you're in a position you're thinking he would act on any suggestions of custody. I cant help any other way but I just wanted to validate that all for you.
Talk to your husband openly about it all.
Finally, everyone's experience of post c-section recovery is different. I remember my recovery took slightly longer than I expected due to slight complications and so my judgement may be biased here but I think that there needs to be some acknowledgement that you're expressing that your in pain. I'd want my husband to be there to help me in pain (not withstanding help with the baby).
Please take care of you. Advocate for you and for your baby. You don’t even need to bring in the conversation you've been told about in order to do this. But I'm sorry that you feel you have to even more because of it.