I tend to carry the ///M sport compressor and goo most of the time. I have a spare that I sometimes take on longer journey's, but frankly flats are so rare that I don't carry it all the time and it's not an easy item to fit in and fasten down. The spare has become more of something if I find a flat in the drive, or if local someone else in the family can drive out with it, etc. Failing that RAC recovery is my friend.
I do however have the jack deep down in the engine bay and jack handle and wheel brace on the boot.