Yes indeed, the logbook is a time consuming part of the coursework portfolio, however IT MUST BE COMPLETED as part of your Unit 1 Coursework Portfolio submission. It is also worth 20 marks (the whole portfolio is 140 marks). The final questions 9 and 10 are the ones that carry 10 marks each, but by completing carefully the whole logbook you are demonstrating to the examiner the level of detail that has gone into your coursework submission.
Here is a guide to completing the log book which you must read thoroughly while you are completing your draft logbook.
You can download a copy of the How To Complete The Logbook document by clinking HERE.