Hi,
not quite sure what you mean, as MSc and BSc for Physio are very different degrees.
First of all the pre-requisites. For BSc just school certificate (with certain conditions); for MSc you need to find a Uni that accepts your BSc as baseline degree. Not sure what a BSc in Sports Therapy is (? similar to Sports and Exercise Science)
Then the time factor: BSc is 3 years, MSc is 2 years.
In both, it is possible to work on weekends and in term breaks.

Also, you say you want to progress your career. Being a Physio does not progress your career, but walks adown a completely different path which has got very little to do with Sports Therapy. (e.g. there is lots of Physios looking after Sports teams on WE, but very few have a fulltime professional career in Sports). Do you actually want to be a Physio? So you have decided on a career change?

Hope this helps,
cheers,
Fyzzio