Oh I’m sure he isn’t a bad person at all! You’re (both?) a bit younger than me (I’m early thirties) and in my mid to early twenties I probably wouldn’t have really thought this stuff through either. It probably hasn’t entered his mind as you’ve both just trundled along like this. If your mat pay is going to barely cover bills then yes, you absolutely need to sort this out ASAP, whether it’s a joint account where your total salaries are split equally or he sends you a decent chunk of cash every month that isn’t expected back. Just try bear in mind you deserve for your standard of living to be equal to his, not a few quid for treats.
You could just phrase it as you’ve been thinking about when baby comes and financially planning and have realised that as you’re going to be a family your current set up of 50/50 bills/rent and occasional loans isn’t gonna cut it without you essentially living in poverty. And that you propose starting to share your money together, not all in one big account (which leaves both of you vulnerable to the other one emptying it and bolting, it happens), but having a joint account where you both pay into and then immediately take equal money out. So you both have your own spending money, savings if possible, that can’t be touched. But you’re on equal footing.
Honestly, a reasonable man wouldn’t have an issue with that. I’d ask him to start doing it now seeing as baby is on the way and you’re going to incur extra costs he isn’t such as buying maternity clothes, vitamins etc. And just see what he says.
I even proposed the other day that maternity clothes come out of our shared money because the baby is equally ours so it’s fair that we both cover baby related costs, semi tongue in cheek but he was like ‘oh, of course, makes sense’. Probably won’t take him up on it but that’s the kind of mindset you both gotta have. We’ve kinda slipped into it comfortably now anyway, my pride at ‘allowing’ him to cover the furniture and carpets in our new home has ebbed away.
Btw, you mentioned how he works hard for his money, but I just want to say that so do you. The amount you both earn isn’t directly correlated to how hard you work or slack off at work. Dental nursing is a tough job, just not brilliantly paid. I’ve never worked as hard in my life as the minimum wage jobs I’ve had in retail, food service, delivery driving, factories etc.