Visit http://email.chichester.ac.uk (Chichester email address)
Or http://email.crawley.ac.uk (Crawley email address)
Login into staff email account using usual staff login details
Click the 'Waffle' in the top left corner

Click Office 365 in the box that opens up

Click on the ‘Install Office apps’ on the top right

It will download the installer and off you go!