A strike cruiser?
What reference site are you using?
Since in battlefleet gothic, and a lot of fluff and the rogue trader rpg rulebook say that while expensive, the warp drives can be fitted on reasonably small ships.
That being transport ships.
So roughly the size of an escort, so roughly 1 kilometer.
(Most in system transports though lack warp drives and gellar fields, which usually result in most of the vessels in 40k actually don't have warp drives.)
There are in fact scout sloops that are slightly smaller, which can also have a warp drive. But more advanced warp drives usually takes more space and thus is difficult and considered too expensive to put on smaller vessels.
But many 40k vessels being relics with odd things on board, resulting in surprising things from time to time. These odd one outs are usually ordered or gotten hold of by rogue traders.
But yeah
@Wraithblade6, the simplest way to have -chip get to the scene, is that the planet it was launched from actually is in system.
Also, i think the confusion with the battle barge stems from a slightly unclear description in the initial description of the hulk. If read speedily, it can appear as the battle barge is not part of the hulk. Which it is.
I think the ship my character was on is sort of smeared across the left side of the hulk. Bent around like a piece of pasta on a shoe.
