Cheers again for the helpful info Kingpr. I managed to get my books onto the Nexus very easily.
Quick update. I got a freepost address to WHSmith customer services so I sent my Kobo back 9 days ago or so. Not had any acknowledgement from them that they are dealing with my problem and no word of when it will be returned.
I have to say that I have lost all confidence in the Kobo brand. Although customer services have generally been helpful I know of too many people (personally) who have had problems as well as people on forums.
I decided to get myself a simple e-reader device purely for book reading. I did look at Kobo devices but decided I no longer felt confident in the reliability of Kobo. I bought a Nook Glowlight. Hopefully the Nexus and the Nook will prove more reliable and have a longer life span!