If you are unhappy and you really don't want to pursue your degree, and you are dead set on being a physio, then yes maybe it is a good idea to switch.
Don't underestimate the worth of a History BA though. Especially one with such low fees.
I've talked to a fair few physios of late, and to be honest, it doesn't seem like a fantastic career path. I'm not trying to slag it off at all, I think it depends on the person whether they enjoy it. Maybe though, before dropping everything to become a physio, you should try and get more of a feel for what it is like to be one? Could you talk to some physios? Or even better spend some time shadowing a physio?
There are so many career paths out there that a solid subject like history opens up for you. What about Marketing, Sales, Buying, HR, PR, Consultancy, Management... I could go on and on. If you study physio you will be much more limited in your options after uni. The key here is work experience. A history BA + work experience has lots of career paths and good jobs waiting. A physio degree + work experience pretty much leads to one job, with limited career progression.
I switched degree course. I'm not sure it was the best choice in retrospect.
Just some food for thought.