I REALLY wish I remembered. I certainly don't remember going to anything prehistoric as a kid.
The best I can do is regularly seeing the sign to Kit's Coty* as we drove past (or as a teenager, I cycled past). I was always interested in Stonehenge whenever it 'came up' but never went, & like others here, loved Children of the Stones....
(*Neither knowing or caring what it was.)
Other than that, I can't even remember my first from once I started actually visiting prehistoric sites. That was around 94-95, as my girlfriend at the time was kind of interested & we both liked stomping around the countryside.
The first ones I can remember are a trip to Avebury & a trip to Dartmoor seeing Belstone Nine Stones http://www.themodernantiquarian.com/site/1298, Cosdon Hill stone row http://www.themodernantiquarian.com/site/4609, Merrivale and a few other Dartmoor thangs.
Don't know whether the Avebury or Dartmoor trip was first & I may have forgotten something earlier!
love
Moth