The building crafts college in Stratford dispose of wood shavings. So when possible I take a bag from the trash and put it in my brothers car boot and leave it in my front garden. Come allotment day it gets brought along and used on the plot.
The saw dust and wood shavings mix is really for the paths which will be formed once the raised beds are in place.
I'll then lay cardboard in the paths and cover with as much saw dust as possible.
The empty beds will then get a turn over. Maybe double dug. And Hungarian Rye Grass seed planed to act as a winter green manure.