Hi, I was wondering if you can apply for an MSc (at a different uni) at the same time as applying for a PhD (I'm applying for a few at my uni and a couple of others), just incase you don't get the marks required to do a PhD? Is this possible as a backup plan?

Yes you can. There is no central admissions procedure for postgraduate degrees, so nobody knows what else you are applying for. When it comes to accepting a place you'll need to be more carefull. Before accepting a place, make sure that you are not then commited to paying the course fees if you change your mind.