Your feed has a fatal error, occuring several times:
<author>firstname.lastname@example.org (David Lees&Thomas Roe)</author>
<itunes:author>David Lees&Thomas Roe</itunes:author>
The ampersand ('&') is used in XML to indicate the beginning of a code sequence: as the sequence is never closed this renders the rest of the feed unreadable. You need to replace it with the code
(which you have done elsewhere). There are six instances altogether of this error.
The 'podcast image', which is correctly referenced in the feed, does not show up when subscribing in iTunes: the images for that have to be actually embedded in the media file for each episode. Please see this page:
I assume that before submitting you are going to replace the existing episodes, which are simply tests, with real ones, as the Store will want to check your material for suitability and will not accept tests.