Hi Ian,
Welcome to this Microsoft Project newsgroup
The only options you have are in Tools/Options.../View tab and use the pick
list for Date Format. However, you should not be entering such dates,
that's Project's job as designed. You enter Tasks, Durations and Precedence
links.
FAQs, companion products and other useful Project information can be seen at
this web address:
http://project.mvps.org/faqs.htm
Hope this helps - please let us know how you get on
Mike Glen
MS Project MVP
See
http://tinyurl.com/2xbhc for Project Tutorials