How long before Gold status is activated?

On my next quick weekend trip to the UK I'll have collected enough tier points on the outbound leg of the trip to get my Gold status [:D]
Is there anyway that on the return leg (I'll be in PE) that I can talk my way into Lounge access at LHR?
I fly on a Friday night, return on a Sunday afternoon.
Is there anyway that on the return leg (I'll be in PE) that I can talk my way into Lounge access at LHR?
I fly on a Friday night, return on a Sunday afternoon.