The postage & packaging is included in the price.  There are no additional charges at the checkout stage. 
A single card is wrapped in a piece of bubble wrap for protection, and sent out Second Class in a larger envelope. (£1.05 Royal Mail 2nd Class)
Box sets are also placed inside a large envelope and sent out Second Class.  (£2.00 Royal Mail 2nd Class)

The bubble wrap I use was once used within supermarket packaging.
The envelopes and boxes are 100% recyclable paper/card. 
Please reuse and recycle the packaging wherever possible. 

(Royal Mail postage costs correct at time of 2022)