I have had a look at the Institute's website. It is not clear, but I would say it is reasonable to have 20 hours in your WBS logs. There is a table at the very bottom of the following link that suggests this. Though it appears to refer to pre-2004 joiners I suspect its intended to refer to anyone who is doing a mix of WBS/PPD as I can't find anything else on the website to suggest otherwise:
https://www.actuaries.org.uk/studyi...d-professional-development-ppd-september-2017
For the log forms, typing them up on the computer and then printing them off to be signed is the approach I took. I recommend scanning them back onto the computer after they have been signed in case they get lost.
Log forms can be sent electronically or by post. I sent mine by post but electronically is probably better. The following link gives more detail:
https://www.actuaries.org.uk/studying/personal-and-professional-development-ppd/work-based-skills
I recommend thoroughly reading everything you can find on the Institute's website relating the WBS/PPD to make sure you cover all the requirements you need. In particular, look at the examples so you know how much detail you need to give. There is a WBS guide and PPD guide that contains most of the information you need:
WBS guide:
https://www.actuaries.org.uk/system/files/field/document/Updated WBS Guide 2018_2.pdf
PPD guide:
https://www.actuaries.org.uk/system/files/field/document/PPD Guide A4 V15 WEB (3).pdf
There are other "Related documents" given at the bottom of many pages on the Institutes' website, so it is worth looking at these as well as they may contain other information not provided on the website itself.
I do sympathise with you - it is not always easy to navigate the Institute's website, and it does not help that you now need to understand and comply with two sets of requirements.