Ok thanks for that...
ive gone through it all giving it a look over, and its now pretty simple
and theres very few (5 over the whole site) div's that have position set on them now...
im not sure what else there is that could be breaking it as its a pretty basic layout now...
getting rid of position on the fcontent div makes the height work properly, but of course with no position it sits at the far left which doesn't work