For UK customers I send via Royal Mail First Class Signed For. For parcels over 2kg, I use ParcelForce 24. The Special Delivery option is there for customers that require full insurance cover on their order. If the items are stock and ready to send, this will usually mean next day delivery.
Overseas parcels are usually sent tracked via, Royal Mail, ParcelForce or one of the major couriers for heavy packages. Delivery times vary.
Please note that I make the blocks myself and run the business single-handed. I always work to make and send orders as soon as possible. If you require your blocks for a deadline, please let me know and I'll do my best to meet it.