If you have assigned copyright to a publisher, e.g. for a journal article, and you wish to include this work within the electronic version of your thesis you need to check that this is permitted. This is a suggested wording you can use to contact your publisher:
I am the author of the following work published by (insert publisher's name):
[Provide a full citation for your work]
I wish to include this work within the electronic version of my thesis, which I am required to deposit in Goldsmiths University's online theses repository (http://eprints-gro.gold.ac.uk). The repository is non-commercial and openly available to all.
I would be grateful if you could advise if this will be acceptable.