Kyosho have a pretty good presence in the UK now, so I assume most model shops should be able to get hold of the shock shafts for you. Try
http://www.kyoshoeurope.com for a list of main stockists.
Personally, I was going to get some bits from RC Champ anyway, so may just tag the shock shafts onto my order.
Whatever route you choose, hopefully they shouldn't prove too difficult to come by.
Did my post convinve you to give them a try too, then?!