I drove over there a couple of weeks ago to see round the museum.
It is only open Sunday's from 10 until 4 and its a fiver to get in, well worth it as I was able to wander freely inside the Guppy. There's no place to get a tea or a coffee though.
When I was there I asked them about whether you could fly in, they said it would be no problem and just to call them up on the radio. They didn't know what the landing fee was.
Would make most sense to fly in on a Sunday when the museums open, there's not a lot otherwise to see there.