Clearly, you need to organise your onward accommodation. If you are buying a new home, ensure you have a mortgage in principle and a solicitor in place.
Start to gather quotes from removal firms like RMV London for peace of mind.
If you have any exceptionally valuable belongings, take them to an expert to assess the exact figure to be sure you have adequate insurance.
Declutter. Go through every room, clearing out what you don’t need and don’t want to take with you. It’s a pain but will save so much time when you arrive.
Start collecting packing materials – boxes, newspaper, bags etc.
Run down your food stores, gradually emptying the freezer and larder.