Time-locked, I'm afraid. You'll have to figure out some kind of "DW - End of Time" stunt to get in.
That's an easy one, assuming dragons can travel in time.
See, the space/universe that is inside the timelock needs to experience information from outside, or else the stars wouldn't shine, the planets would fall out of galactic orbit, and a host of other nasty things that the DW writers handwave away "because magic!".
So, to circumvent a timelock, you need:
1) somebody who is willing to travel to the point just before the timelock engages.
2) sit there through the whole ordeal.
3) not be noticed
And
4) walk off with the goods when the fireworks end.
In the case of the whoiverse:
Dr who sends jack harkness, who has never been to gallifrey before, back to gallifrey using his vortex manipulator.
Jack sits around, watching everybody die. Benefit is that he can't die at all.
He swoops in, makes a core dump of the matrix as the citadel falls, then coasts out into the galifrey orbit around that sun, and takes a couple century nap.
The timelock sets a series of events in endless repeat, but the timewar has consequences outside the timewar, so information must also leave. The timeloop has a lower bound. This means he just has to wait long enough. Gallifrey is rubble. All paths out of time that prevent the destruction are stuck. That's what the timelock does. Jack isn't trying to stop it. He wants a copy of all the timeord's conciousnesses by dumping the matrix. Totally different. All the timelords die exacty like they are supposed to, and events are unchanged.
But the outcome after the lock is different. Now you have acme instant timelord (from concentrate.).
The doctor would never allow anyone to do this, for a multitude of reasons. That's why somebody other than the doctor has to do it without his permission, approval, or help. It is the only way to meet the requirements.
In the case of our fortress, the duration of the event is smaller. Dragon dude just has to chill in "ambush mode" for what, a month or two?