AFAIK you can request hand inspection of all film and cameras. In the
USA the Transportation Security Administration is required to honor your
request.

If you send high speed film through any x-ray there is risk of fogging
T-Max 3200 and Ilford 1600 carry warnings on the box to avoid x-rays.
Velvia and Pan-F are so slow as to be virtually immune to the _carry-on_
x-ray; however, it depends on how many airports you go through, as
radiation is cumulative. Never check any film as the radiation is
extremely high.

If you put your film in a lead foil package the operator just turns up
the "heat" until the contents can be seen.

Don't know what UK regulations are especially with the new heightened
security. I sometimes buy film at my destination -- had no problem
obtaining Ilford HP-5 in Rome and Venice.

Hope this helps,

shin