Mach 75,
Been thru this scenario a couple of months ago.
I recommend chatting to a few property agents and finding out if you can find a replacement tenant for the same (or higher) rental.
I ended up finding a replacement tenant and only then contacting the Landlord. He got a new tenant at a slightly higher rate for a further 2 year contract.
Downside - I had to pay the Agency fee and the new stamp duty on his behalf BUT i did get my deposit back...
Bottom line - its tough getting away without some loss...