Then you need the newly-announced Captain Jack Harkness towelling robe! It will be available from Forbidden Planet from the 15th of November and will allow you or your significant other to indulge in a bit of period dress.
As you can see, the thing comes with buttons and epaulettes and appears to be based on his earlier coat rather than the one seen in Miracle Day. It might well be able to stand up to the rigours of the daily life of an immortal Torchwood operative (no promises, mind), which would allow it to endure perils such as 1874 years of underground burial and being stabbed by a big alien lobster claw thing.
The robe may well not look exactly like that, as it still needs to be finalised. However, if no changes are made to it, you can pick up a robe that looks exactly like that when it comes out for the handsome price of £49.99.