I'm in a tricky situation and need some advice- it's a long one so buckle...

I'm in a tricky situation and need some advice- it's a long one so buckle in! Please don't judge me as I am finding it really hard to express the situation. My fiancé and I have been engaged since January and can't wait to marry, we have booked a band, marquee and location. We are so excited to marry, however I am a full time student. Our wedding is planned for 2020, when I have a job (I'm studying primary education so will most likely get a job straight out of studying) which means we can save up enough for our low key wedding. The issue? We are struggling financially at the moment (not even thinking about the wedding) to pay the bills and rent every month. My partner works full time and I work part time, but we can't make ends meet. From September, the student finance I am receiving will be decreased by half due to my father having a well paid job on the year they look at (he is now unemployed). That being said, I, along with all of my siblings who have finished University, have never received ANY money from my father as he has huge debts and is irresponsible with finances. Student Finance will only accept that you don't receive money if 1)you prove you've been estranged from you parents for 12 months 2)you can provide 3 years worth of paperwork evidencing you have moved out (I have 2 years) 3) if you're married 4)if you have a child. In order to survive financially, the only option we have is for us to marry in a registry office this summer. It breaks my heart to even think about, as I've always wanted a ceremony celebrating our love where I take his last name and we exchange rings. We have the most beautiful church in his home town and I have been so looking forward to having a traditional wedding. I don't want to marry for financial reasons, and by marrying in a registry office we would have to keep it from my extremely religious parents for 2 years before getting a blessing at the church. I hate the idea of not having his surname or a ring on my finger for 2 years and already feel anxious about people looking forward to our wedding. My heart says I absolutely shouldn't do this, but my head knows it's the sensible thing to do. Thanks for reading and I hope I can sort this out so I can look forward to being a Mrs again!