You can access most of the e-resources you find via the Library Catalogue search and discovery tool whilst off campus by using the OpenAthens institutional login available on most major journal publisher sites.
Your OpenAthens credentials are the same ID and password you use to sign into RVC online resources like webmail and Learn.
On the OpenAthens site, click the log-in button top right, then the top link to Login to MyAthens, Choose your Institution (Royal Veterinary College), you should then be prompted to sign into your RVC Outlook/Office account with your RVC email address and password; you may also be asked to approve your log in via multi factor authentication (MFA):

Even if you have logged in using this method, you will likely need to 'authenticate' again when trying to via an article on a journal page. Below are some screenshots of some of the major journal publishers, showing where and how to do so:

BMJ

BMJ’s login menu has a direct link for OpenAthens. Just click it and find the Royal Vet College on the following page to login via your institution:

Cambridge

For Cambridge University Press journals, click the login link and then the bottom link for Log in with Shibboleth or Athens:

On the proceeding screen, click the link for the OpenAthens login page:

Elsevier/ScienceDirect

To view the full text of a Science Direct article in the library’s collection (in other words, an article you can find via the Library Catalogue tool), click the Sign in link in the top right corner of the page, followed by the Open Athens sign in link on the subsequent page. 

Oxford University Press

Sage

Taylor & Francis

Wiley

Wiley is more straight-forward: on the article page, click the Login link > Institutional Login:

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