Can a visitor apply for a visa?

Hi, I applied for my UK Student Visa, but I'm worried that they might refuse it because I didn't include a translation of my bank statement and birth certificate, which are in Spanish. If they do refuse it, I wouldn't be able to go through the whole application process again in time for the start of my course, and I don't think the university will allow me to arrive so late into the course.

To avoid this, if my visa is refused could I go to the UK as a visitor or student visitor (for which I don't need a visa, being Mexican) and then re-apply from there?

You can't switch from visitor to any other category from within the UK.