As with your other question, which presumably is related to this one, you are going to need macros to achieve this, so it would probably make sense to create a document template, with a userform containing a combobox to select the surgery and then write the surgery name and the associated fax number to the document.
I would use a multi-column combo box to hold the surgery details and I would maintain the surgery list in an Excel worksheet, which can be quickly read into the combo box. See
http://www.gmayor.com/Userform_ComboBox.html for example code to read the data into the combobox For the basics, see Word MVP FAQ - Userforms
http://word.mvps.org/FAQs/Userforms.htm for a more in depth explanation, see
http://gregmaxey.com/Create_and_employ_a_UserForm.htm
When a new document is created the userform can be popped up and the surgery selected. The information relating to that selection is then written to the document as appropriate.