Can CX meet you at the agte and bring you thru... (they'd probably like to, but will BA let them)?

Could BA Special Services give you a hand, as a Concorde passenger (sure they could, but they aren't too big on offering)?

Otherwise, you can make it, but it will be tight.

If you ask politely, you should be able to cut the security line at T3...actually, I don't think it will be too bad at that time of day anyway.