Hi ogdesign,
Thanks for the reply. I think perhaps the measurement price calculator has been updated since I last tried it. I've just checked out the new demos from the woothemes extension page and it does seem to do more things than it used to.
I managed to solve my particular situation using gravity forms and the gravity forms product add on extensions. I was able to use calculation fields to work out areas and prices. Gravity forms has the added bonus of allowing you to add other fields, like file upload fields which I needed for customers to upload their artwork. You can also use conditional logic in the forms to only show certain fields when they're required.
Cheers,
Dave