I think his behaviour at the meal was very very cheeky and taking full advantage, as identified by ordering extra drinks he didn't even want.
As you've said several times, he knows this is a tough month financially for you. The whole thing has the hallmarks of a CF.
But...
Someone who is so interested in your ring and its value, more or less a stranger is not someone I would be asking to help me move my furniture across the country. I would be worried that he'd be assessing the belongings for value. Got any valuable paintings? Antiques?
So you've had two red flags already for this very very short relationship.
You have felt obliged to explain almost all your circumstances to him. YOu think you are telling him you are hard up because it was expensive but necessary, but he's hearing spending thousands on private surgery, all the "holidays you've managed to give your son, using savings to pay off your car soon. It's like you felt obliged to apologise, justify and explain, your spending almost asking for approval. If it was really necessary, you shouldn't have to feel guilty and explain. Its enough just to say something vague like you are feeling the pinch. Perhaps be more cautious about discussing so much with someone you've just met. In comparison. How much of his circumstances has he confided to you?
How much help would he really be? Its a complete gamble. Seen it many times with people asking friends to move and the friends turn out to hardly lift a finger, in fact they get in the way.
Why is a nice hotel and presumably further meals needed to reward him? -It is a big ask in a way and better left to professionals with the skills and equipment and space in the van. Presumably, you will also be lifting and you've just had surgery? I can see this being quite a difficult day. Just come from helping with an end of tenancy cleaning and move. It took double the time expected with four of us helping, its grubby, arduous and tiring. You will both be exhausted and it's not going to be the weekend break he is anticipating. You said you were treating him to a jolly. Its not at all moving furniture around and he doesn't sound reliable. Pay someone to do it with the hotel/meal money you would have spent. Then you know it will be done quickly and properly and you won't feel beholden to anyone.
Secondly.
even when the bill came I was hoping he'd say 'Shall we go 50/50?' but no such luck... some of the replies here have made me feel like a tightwad so I still don't know what to think!
I think it would be quite normal to hope for an offer of 50/50 under the circumstances. But he just tucked in regardless, wanting to get his money's worth. That is what has set your alarm bells ringing and why I think it would be madness to go ahead with this moving furniture/hotel break jolly. Whether you want to continue the relationship or not - this scheme would kill it off entirely, I believe. There are too many things that could go wrong. If he lacks generosity in meal sharing - probably lacks generosity in being helpful in moving big furniture across the country IMHO.
Thirdly
you were embarrased with the prospect of him and people on this thread thinking of you as a "TightWad"..
You have to look into why being thought a Tightwad, is worse than running out of money for things that are really really important to you like your son's birthday and your MOT. Managing your resources properly is not being a tightwad. Be proud of managing your money for yourself and your DC, and to hell what anyone else thinks. You felt too embarrassed to speak up - but that is what CFs capitalise on... its a mindset. The fact is if he wasn't being so insensitive, you wouldn't have needed to speak up anyway. You have to ask yourself what's the worst thing that could happen if you had spoken up? Would that be worse than how you feel now? Doubting yourself, worrying about how to get through the month, worrying what people think of you etc... As someone else said don't dwell on the fact you didn't. Think about what you could have said and save that for the next situation.
It sounds like you have had a lot of changes in your life and you are trying to find ways to do things independently, my advice would be to be a tightwad. Make some new rules and Think of some ways of asking for what you want. Dont apologise for what you needed to do/spend. Speak up without guilt or fear that people will reject you - its going against how you were taught in your youth, but again... what's the worst that could happen? Who is going to stand up and denounce you? They may not agree with you, they may have an alternative view. That is a normal exchange. You don't have to constantly do what other people want, and be afraid to say anything. If they reject you for making a proposal about being fair about splitting costs when you have a tight month - what does that make them? Surely they should be the ones to be embarrassed?