When I saw this as a thread I thought oh dear -here's a bit of a laugh, but reading some of the replies, it actually sounds like it might be good idea to have one -maybe in Wales (or a disused quarry), I'm sure people from England would argue "well, they are much the same thing".
If Doctor Who was American they probably would have one (although I don't believe there is a Star Trek one-?)
Building on a few thoughts:
-Entry to the park could be via a Tardis against a warehouse brick wall with the park on the inside of this to try & give the illusion its bigger on the inside;
-I'd have a ghost (monsters) train being at the centre of it all with it also serving as a large inside rollercoaster (like the one at Disneyland) with you in the train swirling around against the ceiling (tunnel walls) so its like the vortex at the start of the show.
-I'd also have a large outdoor water ride with people riding around large circular boats with the centre of each being like the Tardis console.
-I'd also have the main Doctor Who museum including key exhibits based at the park
I'm sure you would get a lot of fans ((tourists) coming there from the likes of Australia, NZ, Canada & the U.S. The other thing in its favour is Doctor Who has now firmly established itself as a British institution so the park would stand the test of time.
It's an awesome idea the more I think about it! -Okay, who's a fan who's got a spare $400M??