As for visits,
I asked the nice folk politely and articulately at Exeter if I would be able to have a peek in the tower. The reply I got was along the lines of "No, we´re so big and important we don´t let people in without an invite".
I then wrote back asking for an invite which I think was a bit cheeky.
Whereas at Plymouth you have to go to the tower to pay the landing fee and can see it all happen!
Would it be possible to visit the approach bits at West Drayton sometime though? Or is it asking too much in these security concious times?
Would love to see it all happen.