From the Gov.uk website: These regulations are not available on the internet and have been amended many times which makes it very onerous to piece together the latest form of the regulations. However these regulations are available in a consolidated format in most city reference libraries, from companies who publish law. One example is Sweet and Maxwell who publish the ‘The encyclopaedia of road traffic law and practice’. This publication is continually updated and Volume 4 contains a full version of the abovementioned regulations in consolidated format. Other possible suppliers include InterRegs. Alternatively, it is possible to purchase printed copies of the Statutory Instruments that comprise the regulations from the TSO.
The document linked here is the original version without the many amendments that have been made.