One thing that might go unsorted and not thought of are your taxes. Now I’m no tax advisor… so I will leave that job for HM Revenue & Customs… But it might be worth giving them a ring as there may well be a form that you need to fill out (be sure to have you NI number at hand when ringing up)
For my situation I need to fill out a P85, I believe this tells the tax people that I’m going to be leaving the country and will be working out of the EU zone. They will also work out any rebate I’m owed as I’m leaving before tax year end so I may have over paid my tax allowance. This has to be done after I have my P45 as I have to send this in with the P85. So I’ll sign the P85 and let someone send it off for me once my P45 comes through.