I would definitely suggest getting a Class 1 medical as soon as possible if you are serious about this career. You never know what might show up - I had a heart murmour as an infant which noone had noticed again until I underwent my initial Class 1 exam which then required a trip to the cardiologist for an echocardiogram. All the faffing about trying to get that sorted almost jeopardised the start date for my basic training a few months after the initial exam.
It's good to have it in the bag...
On a separate issue, I'm not sure it's really fair to compare the likes of CTC, OAT. Apples with apples and all that...What they offer is subtley different and requires quite a bit of thinking about when it comes to assessing risk and the potential outcome.
For example, with CTC you are effectively paying for the training yourself due to the reduced salary you receive after graduation. The repayments are over only 7 years, which means that in the long run you are saving on interest payments, but you have to put up with a lower income for that period than if you were paying it over a more leisurely time-frame...
Just one of the many subtle differences to consider...