There's often an assumption that mothers are the default carers (because they carry the baby and give birth to it) and so the father doesn't need to consult the mother or run his plans by her. If she's not out at work, where else would she be but tending to her baby/children? Your DP may have been raised in a traditional household where the father was the breadwinner and the mother took care of everything to do with the house and children.
You haven't lived together as an independent couple - paying rent or a mortgage and bills. I'm guessing you haven't pooled your finances yet. So your DP may consider his money to be 'his' money, as opposed to shared money - to be spent as he sees fit.
If this sounds like I'm making excuses for him, I'm not. You're about to have a baby and while the pregnancy wasn't planned, your DP contributed to creating the baby and the baby is going to result in changes going forward - changes for both of you. Signing up for a season ticket will have implications for you going forward - financial implications and implications in terms of how much time he can devote to his family outside of his two jobs. He's not showing any empathy to your position in the house - it's not your own home so you'll be stuck at home with the baby and his parents while he's off with his mates. At the very least, he should have discussed it with you and sought your opinion/agreement. Maybe you could have come to a compromise e.g. he can get the season ticket but only go to X no. of matches. Or just go to the matches but no boozing afterwards. Instead, it's been presented to you as a fait accompli so, understandably, you're feeling resentful. And it's not helping that your DP's DM is sticking her oar in.
I don't have a crystal ball so I can't say what the future holds. I'd like to think your DP will be besotted with the baby when it arrives and will step up to the plate in terms of doing his share of the parenting. But it's equally possible that he will continue to live the life of a single man, leaving you to hold the baby. You need a Plan B in case that happens. Whatever you do, don't give up your job as that will provide you with financial security should the worst happen. You're in a very precarious position at present in terms of your housing. And be extra careful with contraception after the baby comes. A second unplanned pregnancy could sound the death knell for your relationship or leave you trapped in a difficult situation.
Also, I wouldn't be happy with his parents defending him by saying that he works hard. I'm sure you work hard at your job too. The implication seems to be that he works hard so he can spend his money however he wishes. You're having a baby together and that should be his priority. If you were living together and paying rent and bills, they would have to be his priority.