We moved two weeks ago, and apart from my acres of books which are still in boxes waiting for shelves to be put up, we are pretty much straight.
We started packing just after exchange - so just two weeks to do it in. Hubby and I then took the day off before moving day and just stripped the place bare. We left our son's room until the day before so everything was 'normal' for him right up to the last minute.
The removers brought hanging boxes with them for our clothes which we packed on the day. With the other boxes we labelled what was in them roughly and which room in the new house they were supposed to go into. This worked reasonably well, the kitchen stuff ended up in the kitchen, however, some of the boxes ended up in the wrong rooms, but once we started unpacking it didn't really matter at all.
Would it be a good idea to have a meeting with your removers to find out what kind of system they like? Do they prefer colour coding, or do they like just a vague idea? It would cut down on the guess work.
I brought some cheapy crates from Homebase and packed all the essential stuff in them, like the kettle, coffee, food blah, blah, blah. We put all those things in the car and took them ourselves. I'd also recommend having a box of cleaning stuff put aside as well - we left our old place as clean as we could and I wouldn't put anything in the cupboards in the new place until I had given them the once over! The tip about taking your bed linen in the car was also excellent. The beds were the first thing I made up and I was so grateful I did.
We collected our ds late Friday afternoon on the day we moved (he's 3) and he had a great time running round exploring. He helped me get his room straight, putting his books on his book shelves and getting his toys out. He had a lovely bath in the 'new bathroom' and went to bed only about an hour later than he normally does. We had a minor upset when he said he wanted to go to bed in his old house, but it didn't last long and by the next evening he went to bed no fuss.
Good luck. I'm sure it will go very smoothly on the day.