This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
The complete Estes range of kits and motors are available (not Estes E15).
The Estes range is imported/distributed by Ripmax Ltd (See addresses below).
Recently, a range of 'Launch Pad' kits has been made available by mail order
from a company called Advanced Rocket Components (See addresses below).
These will fly on Estes D and Aerotech E15/E30 engines. I do not know of any
other source of rocketry components in the UK.