The business use % for related expenses does not need to come from a logbook. You will need to make a reasonable estimate.
For example, you could estimate how many hours you drive for Uber each week. In this example, lets say 30 hours. Then you would estimate how many other hours you use your mobile phone. Let’s say it was 10 hours. This is a total of 40 hours use.
To find the business use %, divide the amount of hours your phone is used for business (30hrs) by the total amount of hours (40hrs).
30/40 = 0.75.
Business use % = 75%.
Just remember, for all related expenses you need to be able to justify why you are claiming the expense as a business expenses. You also need to justify how you calculated the business use %.