I have used packers twice now, once for own move and once for elderly DPs. They are really good, it transforms the job and quite frankly there’s not a lot you need to do.
Anything staying in the house - label. E.g bathroom cabinets, towel and toilet roll holders, mirrors, curtain poles etc.
Any expensive light fittings you want to take need to be taken down and replaced with standard flex and fitting for a light bulb.
Sort out all the spare keys that belong with the house and label for leaving behind. If you have anything like remote controlled garage doors leave those too.
You probably have these in essentials/urgent but make sure you know where the kettle, mugs, teabags, milk etc is! Get in biscuits for the workers. Sort out what you are eating on moving day and what with (plates, knives and forks etc).
If you haven’t booked a ‘moving out’ clean, keep the hoover back and any tea towels/washing up liquid/cloths/cleaning stuff. Unless you are Mrs Hinch, when they take out the fridge/cooker/washing machine it’s going to need a clean in the empty space. You may find empty kitchen cupboards need crumbs wiping out etc.
Have labels ready for where you want stuff to go when you get to your new place if it’s not obvious.
If there are any potential difficulties about finding the new property, make sure you have written down instructions for the removal people.
With only two days to go it’s probably too late to get rid of stuff that you don’t really want anymore, but if you can do a charity shop/tip run, so much the better.