Bismillahir Rahmaanir Raheem
Al Jawaab Billahit-Tawfeeq
Please refer to this link with regards to your question about marriage without parents' consent: http://www.muftisays.com/qa.php?viewpage=viewQA&question=56
About studying, my advice to you is to consider furthering your education. Nowadays, the younger generation do not have the zeal to further their studies. One of the main excuses they put forward is, 'What's the point in furthering the studies since after high school, we're straight away going to get married?'
If this was the mentality of every person, then what would happen to the future Islamic generation? There will be no intelligent 'aalims, muftis, Muslim doctors, Muslim engineers, Muslim accountants, etc. These roles will then be taken over by the kuffars and they will have all the more reason to look down on Muslims worldwide.
There is no valid reason to put seeking of beneficial knowledge to a halt. The Sahabah (may Allah be pleased with them all) used to dedicate their spare time in learning deen. This was also true for the Sahaabiyaat (may Allah be pleased with them all).
One prominent personality was Sayyidatina 'Aaishah (may Allah be pleased with her). At such a young age, she became one of the narrators of hadeeth. Apart from that, the Sahabah (may Allah be pleased with them) used to go to her for advice and consultation in matters of deen after the demise of Nabi (sallallahu 'alaihi wasallam).
If we do not attain beneficial knowledge, then how are we going to educate our children in the future? After all, the mother's lap is the child's first madrassah (learning place). If the mother is well equipped with beneficial knowledge, then insha Allah, her children will be able to be nurtured into becoming fine Muslims and Muslimahs. However, if the mother was not properly educated, then the children too will suffer the consequences later in life.
If you feel that you do not have the interest in going to university, there are now many distance learning courses available to the public. In this manner of studying, you will have more control of your time (ie. do not have to do everything in a rush). You can take as long as you want in completing your studies and you do not have to even attend tutorials and lectures. However, please remember in pursuing higher education, or anything in that matter, the Shari'ah laws must not be breached in the least.
I highly urge you to rethink about this matter again and consider what your parents want you to do. They are the ones who went through all the hardships and difficulties in raising you up. To obey and carry out their wishes is the least we can do for them to repay their kindness. In actual fact, nothing that we do for them in this lifetime can compensate what they have done for us.
And Allah knows best.