Finishing the course during the holidays is good if you remain hardworking throughout the rest of the year as essentially, after learning the course all you'll be doing is revision and refinement. However, I for instance, wouldn't have had any chance whatsoever of learning the methods course entirely on my own, I would have needed some assistance. Also, it's very difficult to have the motivation to do a years worth of work over a few weeks.
If you do decide to finish the course, make sure it's one that you personally find relatively easy to understand. Take extremely good and detailed notes from your text book and do practice questions from your textbook to make sure that you are actually digesting all of the information. Read over all the notes you've made every day so that you don't forget what you have learned.
This is a very big task! You do get some benefit from it, but it certainly isn't required to get a 50 in the subjects. You need to also make sure you actually get a break these holidays too because you won't get another proper one until November.