tough call. speaking from experience, one of the very few regrets i have is that i didnt finish my degree sooner. instead, i let uni to work in a bank. a young guy and a few $$$ in his pocket are soon seperated. especially by the beer goblins.
i dont want to sound disrespctful, but fitting mufflers for $500 a week is not good money and offers a very limited future. you may not get a job in your chosen degree immediately, but once you have done the entry level work, you will have some experience and a foot in the door. it took me 3 years after my degree was complete to work in my field, but i love what i do.
but, ultimately it is your decision. there are a thousand things you want to do, and limited $$$ and time, and whatever you chose, you will miss out on something else. good luck