I would strongly recommend doing a dummy run, not just to see if things fit, but also to check weight. Ideally you want to do this before the packers come to get your stuff, so that you can put any excess into the container. Otherwise you'll have to ship it separately.
Most airlines are fine with a kilo or two either way. Do be aware that the scales at the airport and your home scales can be out by several kilos either way. Portable luggage scales can be very handy in proving that you packed to the weight allowance.