Right, I've been chatting with someone who knows this stuff and it's not as bad as it sounds. You get six sittings but you can have a go at all of the subjects from the start. Each subject is covered in approx. 12 multiple choice questions at the exam, so doing all of them is certainly possible in one sitting. It's been done in 1.5 hours but if you take your time you can expect to take 3.5-4 hours. If you pass three of the subjects, the rest can be done in the second sitting and so on. If you pass eight subjects during the first sitting, you only have one left to do in the next sitting. By doing this all in one go you actually get the chance to link stuff together a bit more than when doing one subject at a time. It may not be everyone's choice to do it this way, but you've picked a good set of training facilities who can help you with this.
I would have a good chat with your instructor and the people supporting the theory side as they will be best placed to advise you on when to do what. There is a reasonable period within which to take part in those six sittings for the PPL theory exams, and from there you've got an additional 24 months to get the practical side buttoned up. Any advice we would provide on this would be no more than a guess, while your instructor(s) can see where you are, how you're progressing and what would fit your needs/capabilities.
And remember: it's supposed to be fun!