31 years old here, Currently in my penultimate year of an economics degree. It's hard to give advice on your situation since no one can guarantee you'll get a job. The only thing I can suggest is that before you make the decision, do your research. Look at how many grads from bio science get into employment after one year, Figure out where you want to work, if you'd be happy to move etc and know who the big players are in your industry and what the job market looks like. Also be aware that even though you feel settled in what you want to do now, you might find over the course of your degree that you want to change your goals or work in a slightly different field.
Finally don't do a degree you aren't interested in! Even if it seems like a good shout at first because of the eventual career benefits you have to remember that for the next 3 or 4 years this will be your job and you don't want to add "hate my degree" onto the list of typical mature student worries.
Good Luck!