it was strange, i called manchester and they took my plan over the phone, last night when i get back i called leeds to close my plan as manchester weren't on the phone,
the lovely lady on the line said apparently manchester are due to close at the end of this month with all flightplans being sent to swanick from now on.
I didnt get a fax number, however swanick can be contacted on: 0845 601 0483 for any more info
hope it helps
though i dont recall being told in the past manchester fpl were shut/closing