I'm thinking of doing Ancient History as an elective for year 11 and 12...do you think i should??

No one here should say yes or no because ultimately it comes down to whether you want to do it. You're on this spot so you must be interested in it.
I did history for year 11 and 12 and it was the best lesson out of all of them because i enjoyed it :) i studied medicine through time and germany

yes i have done it since it began in yr 11 i love it i have loved it since i was 7

well, it all depends on u. u can if u want i guess. but i think being an archeologist is cool. learning about our past and shtuff

The choice ultimately comes down to you but here are some pro's and cons.

PRO-
can be very interesting
many civilizations
a lot of mythology, which is usually interesting
AND MORE
CON-
can be boring or hard to read
sometimes mythology can not make sense

That's all I can think of, if it were me I'd do it. So yeah, follow your heart and do what you want!