You're right about the Primer - although it looks like clay, it is actually metal. The restoration job is pretty extensive on all the Tanks, but they don't try to make them look 'as new' - many (King Tiger) etc still with bullet/shell holes in the thinner plating, and general 'battle damage' clear to see on track covers, sprockets etc.
There is a PC based 3D 'walkaround' of the inside of the King TIger, showing both pre and post restoration. The quality of work is superb, but unfortunately, you can't get in to actually see it !
In those tanks that you can look into, the other thing that you become very aware of is the confined space inside the Turret. The fact that you are being thrown around all over the place, plus the noise and heat from the main weapon, along with the clamour of shells etc hitting the hull - must have been absolute hell.
It is well worth a visit, especially as Bovingdon is a live 'Tank Town', with most of the Tank Corps facilites there. It is quite strange to be walking around the relative quiet of the museum and suddenly hear the roar of live Tank engines as three of the latest (Conqueror/ Challenger ?) charge past at 30mph not 30 feet from you !! - Very impressive.
In the Summer months, they also have Tank Days - where you can 'buy' a ride in two or more vehicles (at least one heavy Tank). If I remember correctly it's about £85 - so if you do visit, you might want to check the dates for these events.
And finally - yes Nexx - I use a Canon D10 Digital SLR with (in this case) a 35-85 Zoom lens. I have slightly tweaked the exposure settings, but by and large it is pretty well standard - I prefer to adjust my photos in Photoshop to get the required Contrast and Lighting. (As stated in an earlier message, I haven't yet adjusted these - might start with a German Heavy !) Unfortunately in situations like this the 1.6 magnifying effect that is standard in most Digital SLRs is a bit of a pain (whereas at Air Displays it is a real bonus - taking my 300m lens out to 480m equivalent) - so unless you have a true Wide Angle lens, confined spaces can be a bit of a problem.
Regards