[Lee]

Menu button (top right, 3 horizontal lines) has the following options:
‘View New Posts’ & ‘View Today’s Posts’
Seems to do the job already?!

No - these just give you a list of threads.

The link I refered to was on each threads page, and scrolled down to show you any posts you hadn't read.

Redshift - do you mean clicking on a thread and it taking you directly to the first unseen post?  If so, you can do this by clicking the green arrow next to the thread name.

 
Thanks Simon, that'll save me trawling through the settings