Just to update the members, I've made contact with a European supplier who will be able to supply these at a very good rate, but also will be able to get selected batch numbers from JSB. He lives right next to the factory.
Whilst I'm sourcing these from Rotheries at the minute (and they have been helpful telling me which batch numbers they have in stock right now) they only can give me the batch numbers they have themselves. This new route will open up the full inventory of batch numbers hopefully.
The price 'should' be cheaper, depending on the transport costs.
In case anyone is wondering the batch numbers available from Rotheries right now are