I could kick myself... I really spent ages going through everything before I clicked submit!
I don't think it should be a problem like you say, as it is only the declaration forms and I am pretty sure it wouldn't be too much hassle for them to print a couple of declaration forms with her married name on, it's not like I made a mistake on the actual proper application.
However, I did email this morning before work and got a swift reply pointing me towards a website where I filled out the form there and sent it. Now just got to wait 24 hours and hope they reply.