I would like to use your forms for collection of confidential patient data (I am based in the United Kingdom).
Is it possible to collect data securely or preferrably without saving anything on your server?
Alternatively it possible to completely wipe the data off your server once the responses have been downloaded? I notice that there is a funciton where you can go back in time to previous versions of the responses table - is it possible to disable this?
No, at this time there is no way to disable the history. You might have a look at this document on FormsCentral security: http://forums.adobe.com/docs/DOC-1384
Regarding collecting responses without saving anything on FormCentral servers you can still use FormsCentral to create PDF forms and use traditional methods of submitting responses such as email, saving the PDF without a Submit button and adding a Submit button of your own.