The University website outlines information prior to starting, including moving to Oxford and accommodation, when you start such and general information about the University.
There is additional information for international postdocs.
This document has lots of information about Moving to Oxford.
The Chemistry department also has information for new starters - but this can not be viewed until you officially start.
Work+Family Space for University of Oxford - find information here: https://www.myfamilycare.co.uk/oxford
This document outlines your terms and conditions of employment in addition to those detailed in your contract of employment.
Grade 6 + http://www.admin.ox.ac.uk/finance/pensions/uss/
All employees will be enrolled to the appropriate pension scheme from month one.
Pay dates are monthly with very specific cut off dates.
Support for researchers
This provides information for research employees in the form of guidance on career planning, research funding and grants, wider engagement and libraries and resources.
Benefits of working for the University
http://www.ox.ac.uk/about_the_university/jobs/benefits/ and http://www.admin.ox.ac.uk/personnel/staffinfo/benefits/
The University has a wide range of benefits available to you. The above two sites includes information about travel options, childcare and family friendly policies, discounts and personal development.