Thanks for the advice - I went for it and it seems to be working.
No sure why my incident module is different to this new one - unless it's a throw back from previous versions/upgrade but obviously knowing that I have to tick the box on my incident process to make it work meant I hadn't gone any further with this one and hadn't actually tested it!
Anyway - all appears to be working fine now.
Thanks for the advice re date - I usually use UTC calculation, however this notification was different, future dated dependent on attributes selected on a previous window so different calc required in this case.
Thanks again
Hayley