OK so after much investigation I managed to get this working with setup as below (list is order of installation). I have a Lenovo T410 iCore 5 laptop with 4GB memory:
64-bit Windows 10 Pro (clean install)
32-bit Microsoft Office 2016 (i.e. Outlook 2016)
iCloud for Windows PC (current version is 5.1)
BitDefender Total Security 2016
DO NOT install 64-bit version of Office 2016 as not compatible with iCloud which installs as 32-bit only on 64-bit Windows 10. I also found out that deleting the first user account used to install software also seems to corrupt things and I had to repeat the fresh install of Windows 10 and other software! I kept getting messages that Outlook wasn't my default mail app even though it was, and Outlook wouldn't play ball with iCloud or the BitDefender anti-spam plugin!
Hopefully this saves some people a few hours of frustration and wasted time!
Cheers,
Dom