5 months including the 14 ATPL exams??? Surely this can't be right? Even if you self studied and were Einsteins long lost illegitimate great great great grandson thrice removed the system is against you. For a start you need to enrol with a course provider, then attend their brush up course (2 weeks generally). Brush up courses are usually provided for each module. If you plan on attempting to sit all 14 at once then you will need to attend the relevant brush up courses which might not be run in the month you want.
Then you need to enrol in the exams. This needs at least 3-4 weeks advance booking to ensure you get your preferred centre or else you might be flying to Glasgow and accomodating yourself for the week up there. The results take weeks to come out by which time you have missed the deadline for the following months sitting. You are not allowed to book without having your results so this precludes doing a back to back sitting. Then any CPL/IR FTO who is worth their salt will more than likely not accept your course booking knowing that you haven't passed the exams. The best FTO's have waiting lists for their courses which can be many months in advance. You can go cheap and cheerful elsewhere but buyer beware. In the UK the ME/CPL/IR is going to take a MINIMUM of 3-4 months depending on weather. You can cut some time off if you head off overseas but you won't get it done in half the time or anything like that. At the end of the day there are only so many hours you can fly and your brain will more than likely be fried after each flight anyway. Then there are other factors such as instructor/aircraft/training slot availability to contend with.
5 months - highly unlikely if you have to do the 14 ATPL's. More like 9-12 months and that assumes you pass everything first time and are extremely clued up on the theory side of things. Most people tend to take a year at least just to do the ATPL theory side of things when self studying. Many more run right up to the 18 months deadline which can be quite tight if you can't commit 100% to the study and need time off for a home life.