student visitor visa

I have procrastinated a bit in applying for my student visa to study in glasgow this fall and now I can´t even get an appointment until after I would like to leave the country.
I'm wondering if anyone knows anything about the student visitor visa. My program is for one year but is it possible to go for 6 months, leave and then go back to continue my 6 months both times as a student visitor?
Failing that how long does it take to actually recieve my passport back?

unfortunately, you still need a visa to be able to go to school there; they'll ask for a clearance when you register.
Can you go to another VAC? The turnaround time is very quick.