Sorry Callum,
don't know how this got missed..
by sub template I mean which view template - default or flex2.. sse screen
with either all you need is to comment out the tab code and the desc and related will show.
Then style them as you want
in default it is all code from templates/yoo_balance/html/com_virtuemart/productdetails/default.php
comment out from line 781 to 827 - that gets rid of the tabs
<!-- <ul id="vmtabs" class="shadetabs">
...........
</ul>-->
then line 902 remove the display none
<div id="relcategories" class="tabcontent" style="display:none;">
to
<div id="relcategories" class="tabcontent" >