Ajax wrote:
[...]Anyone know of a RF noise generator / jammer,
that could operate in VHF frequencies?
Preferably in UK / Europe. Ideally a radius of 20-30 metres[...]

If you are planning to interfere
with a signal transmitted by someone else
and meant to be received by someone else,
the first step of this is to contact your solicitor;
have him describe the process of posting bond.

In the USA, the limit for an unlicenced transmitter
is 100mW (0.1 Watt) and it is a criminal act
to interfere with someone else's transmission and/or reception.
The details are likely similar where you are.

If you want to eliminate ALL radiant energy
in a location on YOUR property, this is the standard method:
http://en.wikipedia.org/wiki/Faraday_cage
(Windows / glass doors will pose a particular challenge.)

You may already have some nutters about
who can give you pointers:
http://en.wikipedia.org/wiki/Tin_foi...opular_culture

If you then want to introduce radio-frequency signals
into that area via a cable / transmission line
and *exclude* one part of the spectrum:
http://en.wikipedia.org/wiki/Band-stop_filter

Any NON-passive method will soon involve the authorities.