badgermark,
I send pedals through the post by, firstly, padding out the inside of the pedal box with bubblewrap to stop the pedal itself bumping around inside it's own box.
Then I either pack the original box inside another , slightly bigger, box (packed out with bubblewrap). OR I put one layer of bubblewrap around the original box and then fashion another outer layer of cardboard from whatever's lying around. Plenty of parcel tape finishes the job.
Can you tell I love bubblewrap (oh, and parcel tape !) !! The method I have described should be pretty much foolproof.
You can't beat the Post office for sending packages up to about 2kg. Use first class and ALWAYS get recorded delivery ( a bargain at 70p). From 2-4kg, standard parcels is probably the cheapest, but is SLOW. Anything heavier than that, then I would buy a parcel delivery through ebay. These are usually via parcelforce, and are just bought in bulk by a middleman, so you can get it cheap. Just logon to ebay and search for "parcel delivery".
Alan