A VFR flight plan must be filed at least 60 minutes before clearance to start or taxi is requested. Normally the flight plan is filed at the departure airfield that will pass it on to the relevant Parent ATSU Flight Briefing Unit. If the departure airfield will not be able to file the flight plan, it should be telephoned or faxed directly to the appropriate Parent ATSU Flight Briefing Unit:
London/Heathrow
TEL: 0208 745 3111 FAX: 0208 745 3491
TEL: 0208 745 3163 FAX: 0208 745 3492
Manchester
TEL: 0161 499 5502 FAX: 0161 499 5504
TEL: 0161 499 5500
Scottish ACC
TEL: 01292 692679 FAX : 01292 671048
TEL: 01292 692663
The ATSU or FBU must be advised as soon as possible of any cancellations or delays that will exceed 30 minutes, or changes to flight plan details.
If the flight lands at a place other than the flightplan destination, the destination must be informed within 30 minutes of the planned ETA there.
The above was taken from the 2004 UK VFR Flight Guide by AFE. Just thought it would help..
SSC