VFR Transit
I am a student and am about to plan a flight over to LE2K to complete my cross channel checkout on club aircraft, However it is me who needs to complete the flight plan and I can't register for an account
You have mis-understood. The NATS facility under discussion is a future thing. The UK has never before had an online flight plan filing facility, so this is a very desirable thing.
To file a flight plan for your flight to LTQ
today, you should consult your instructor. You will file it using the present means, which usually means filling in the flight plan form and handing it to the tower.