What would you do re TTC or job you enjoy?

Hi All, first post here so apologies if this is in the wrong topic. Partner and I are getting married soon and I have a 7 year old stepdaughter. We'd love to start TTC soon. However we've got a bit of a dilemma. I like my job but it doesn't pay enough to be sustainable long term and the only way I can progress is to go back to university. We know if I do that there's no way we'll be able to afford a child until after graduation. We know you get extra money for having children but that still wouldn't be enough to cover childcare etc. Open University isn't an option for the job I'd like. I'm currently looking at other jobs, they pay better but are not overly enjoyable. 

My question is this, would you give up on pursuing a career you find fulfilling and enjoyable in order to TTC?