I will happily share the list I created for myself, though I still haven't determined what needs to be done in what order:
Before Departure:
-health insurance, if you are not covered
-assure that mail is forwarded to a retrievable location
-all utilities and services are cancelled
-notify bank of your travels to prevent problems -- if you have a foreign tel#, provide it to them so that they can reach you
-get your cell phone unlocked if you intend to use it abroad
Once there;
*Embassy Registration (you don't have to, but if you are there for more than six months it may helpful if there is an emergency)
*Apply for National Insurance Number (best to do this ASAP as it can be a time-consuming process)
*Open Bank Account so that your employer can pay you

)
*Get cell phone
*Get travelcard (need photocard for passes of 7 days or more which requires passport photo)
*Council Tax registration
Hope this helps.