Well just to update anyone else with this problem searching the board. The only way I could get it to work in the absence of a reply to my post, was to edit the formfield.php file, line 265 to get rid of the div and span tags, (perhaps they shouldn't really be mixed in there as they are for presentation rather than functional elements within form controls, no?).
The comments in the formfield.php did point to using another file DefaultFieldHolder.ss that should be used to implement a custom look, however this isn't elaborated on as to how this is achieved unfortunately. I did try by placing it in my themes folder and doing the flush=1 trick but it didn't appear to get picked up by SS when placed in there so I'm none the wiser as to it's proper usage or context.... :o(
Can anyone from the team help to expand on how this file (DefaultFieldHolder.ss) works to create a custom look to forms in the app please?