I got to BHX early for this very reason, they didn't open the checking till 35 mins before the flight so it was a run for security straight to the gate
that's also who I used. Did the test Saturday morning and posted it before 12 in their drop box , had an email 4am on the Sunday with the results.. also had a discount with KLM code
thanks for that info, I will delay a week and if not come through use the visa exempt entry, just don't have a flight back as I am picking up non b paperwork once I get there