Thanks for the advice. I'm still a little nervous about travelling with Delta 3200 because of the X-Rays, but in fact I've never (touch wood) been refused a hand inspection when I have taken it.
I'll try and get some microphen when I'm next in the big city, and try it out with HP5 and Delta 400.
How about pulling the 3200? Still Microphen recommended, or would the DDX be a good choice in this case?
Changing the subject a bit, most airport X-Ray machines say they're safe for up to EI 400 film, and I've had no reason to doubt it. Would this still hold true if you plan on using it as 800 EI film?
Again, thanks for the prompt replies. My house has been renovated, and I've almost got my darkroom back so am anxious to try this out.