I know the friends he is seeing on Saturday, and they know me well. So I can't imagine that he is going to be getting a whole one sided, 'aww you don't need her' kind of speech and filling his head with the perfect bachelor life with new women and lots of sex. These are both men who are settled with long term partners, and one has a child. So hopefully my husband can get some thoughts sorted on Saturday with their support
Don't imagine that you can rely on your h's friends to fight your corner as it very much sounds as if his mind is made up. If this is the case, it's highly unlikely that anyone will be able to change it and, unless they want to risk the cooling or ending of their friendship, his pals will no doubt align their opinions with his and maintain that ending the marriage is 'for the best' or some such platitude.
Regardless of whatever communication you may have had with your h to the contrary, you're entitled to change your mind and return to the marital home whenever you wish and I would advise you to go home tonight before your h finds further reason to dissuade you.
With regard to finances you don't need to have any plan in place at the present time and if he should propose a change from the status quo simply say that you'll consult a solicitor and get back to him.
What is important is that you stamp your authority over that which he's trying to wield and, as I see it, the most effective way of doing this is to take the fucker by surprise and return to your home tonight or first thing in the morning. You can go out for the evening tomorrow while he entertains his friends, or tell him to entertain them in a pub.