What I think, and admittedly, not being an expert, is that you can rule out the factor of fun and adventure. You are not in the right frame of mind to jump into adventure, and the unknown is tricky when you have young children. You have to put the little ones first, and risk will affect them adversely.
Surely, having debt is an issue in the ME and treated as a crime, if everything goes wrong?( Sorry, I'm no expert). Possibly, regardless of where you acquired and accumulated the debt. Anyway, in Britain, you have social security and the school to help signpost you to help if your little one has some additional needs, or you don't feel strong.
I hate to say it, but being very cynical, your partner might be thinking that, yes things between you are not great, so if you and the kids are with him, under his eye, you won't start divorce proceedings, or speak to friends, who, like many respondents on this thread, will urge you to consider your own wellbeing and needs ( and put the kids first) and think independently.
If he thinks that, the way things are going, you might split anyway, it might focus his attention on the annoyance of this and how to make sure he is not negatively impacted by any split. He might be trying to get more income because he thinks you might split: goodness forbid, I hope he isn't thinking that if you divorced, he'd have more rights there and power. Maybe he thinks you'd take the kids if you split in the UK, and he'd not get to see them on the terms he wants. We don't know him, and only you do, but even to thrust this surprise job offer on you, doesn't sound like an open, collaborative person.
I don't think that men think that they won't be able to cope with their own children for long periods, without their wife's help, if they meet a new partner who might have extended family to help. You just can't predict the future.
But enduring awfulness feels worse than renouncing the heights of experience and adventure. So opt for what you know and safety.
Posters sound genuinely worried for you, and not just giving their opinion. I am worried for you too.