Am I being paranoid if I fear that one of the harder to get components of a
suitcase bomb is detected on airplanes traveling from Russia to England.

Suitcase bomb would use plutonium and that needs U238 under the lead shield
as a neutron reflector as well as Polonium 110 and Beryllium dust injected
into the critical mass of plutonium (34 pounds) to achieve detonation.

Lead and Beryllium are easy to get, the harder to get items like U238 and
Plutonium are dangerous but not as dangerous as Polonium 110 and Polonium is
an Isotope that has a shorter life than that of U238 or Plutonium. An old
(taken out of service) nuclear weapon would require the electronics, the
shaped charges and the Polonium replaced to insure detonation.

As to the political aspects of using Polonium 110 as a poison, the only
countries that make it are France, Russia, India, Pakistan, China and the
US.