In order to carry dangerous goods by road in the UK and across most of Europe the driver of the vehicle must have an ADR Driver Training Certificate in order to prove that they have participated in an approved training course and passed examinations.
You requirement will depend on the mode of transport and the class or classes of dangerous goods that you intend to carry.
You must undertake the Core module, which explains the basics of ADR and includes practical exercises including; Emergency Aid, Fire and Actions to take in an emergency.
The modes of transport is divided in to two categories:
GOODS IN TANKS; which includes Road Tankers, De-mountable Tanks, Portable Tanks, MEGC's, Etc
OTHER THAN IN TANKS; which includes Package Vehicles, Tippers, Skips, Etc.
There are different classes of Dangerous Goods, although Classes 1 & 7 (Explosive & Radioactive) are not generally included as part of a standard ADR course, you must take whichever classes you intend to carry.
As an example, a Petrol tanker driver would need (at least) Core, Goods in Tanks and Class 3 Flammable Liquid
Class 1 & Class 7 Courses
Dangerous Goods Awareness
Management of Dangerous Goods