The Yuba Mundo cargo bike now has a UK distributer; This Is Loads Better (who also sell loads of other cool bikes).
The Yuba Mundo offers "environmentally friendly transportation, economic viability, unsurpassed cargo capacity, the ability to carry passengers, healthier commuting and affordable mobility". The Yuba is based on the Xtracycle long bike system.
If you order before the end of the month, you can get the 6-speed version for £380, instead of the usual £425. Ten percent of every order goes to the Re-Cycle charity.