it's very very hard to take up a language after missing out on 4-5 years of the course. you will have to learn basic vocab and everything like that. you may need to talk to the teacher about it but if you really need a language spanish is the easiest one to do.
I'm considering doing the same, I've been using apps such as duolingo, mango languages and memorise...does any one know what dialect the Spanish exam is done in? I've just been assuming it's spains common one??
Go for it! I've been self studying Spanish since 5th year since it's not offered in school, and honestly it's not that hard, (kinda been confused with French but haha) I've been using memrise and duolingo and they're great!
i tried to take up 5th year Spanish, there was a lot of new vocab to be learned ALL of the time and it was just daunting like with Higher Maths and everything. my mom signed me up to a Spanish Immersion course with Stein Study, here's a link to one of their blog posts, can't post pics here I think
it was really fun and got an A2 on my LC, all thanks to that and I could get that vet course I wanted :D
So good luck and go for it, but don't forget there's always a lot more help out here ;)