Hello Aaron, that must have been great trip to the Isles of Scilly but I don't think I'm going to be able to be much help with the lichen....
Cladonia pyxidata - Alan Silverside has some good information here re C. pyxidata and C. pocillum:
Cladonia pocillum (images of British lichens)
Caloplaca marina - doesn't look right
Caloplaca marina (images of British lichens)
and possibly it might be Caloplaca littorea instead
http://www.britishlichens.co.uk/species/Caloplaca%20littorea%20large.jpg
Both your Roccella's look good, though that is only from photo comparisons and details in Dobson's 'Lichens'
Not much help I'm afraid, you need AlanS for these!