Try 6 months, if 2 months, cic might think it's not a super visa app, you can always shorten the stay, no one can stop you from leaving.
Just remember the medical insurance is for 1 year, talk to the insurer if you plan on leaving early to refund the remaining months premium.
Just remember the medical insurance is for 1 year, talk to the insurer if you plan on leaving early to refund the remaining months premium.