I haven't had any problems with shrinking with water etc, but I only dry clean the uniforms once every few years when they get too ripe. They have made it through rain storms and mud and seem to hold up alright.
If you want, to do a bit of fine tuning to the kit to look more the part of the Guardsman, you can pull out Jerry Lee's tags, and on our "Download" page you will find a tunic and trouser label. The tunic label has the size written on in pencil, and is glued inside the tunic opposite your right hand breast pocket. The trouser label is the same way but is glued on the outside of the rear left hip. Here are a few links that will help with the description.
http://meltingpot.fortunecity.com/utah/894/uktunic.htm
http://members.fortunecity.com/milit/trousers.htm
Polish up the brass buttons and belt hooks, choose a Regiment to put on the proper shoulder titles, and you will be set to go!
Cheers!
Jim
Lt. J Higginbottom
BEF Company Officer (GWA)
2nd Grenadier Guards
Guards Division