Day 2 lateral flow test - flying out 21st and returning 28th

ontheflyaccount

Hi!

Having already wasted money on antigen tests to get into Portugal that aren't now needed (the rules changed the next day!), I am trying to work out if the following is the case for returning... 

1. Order lateral flow test from 22nd October whilst we are in Portugal
2. Get code that we put down on passenger locator form completed max 48 hours before returning home (on 28th October)
3. Test is posted to our home address and we do by day 2 (30th October)

Have I understood the rules correctly? That I don't need a test reference number or passenger locator form to leave England, and that I will receive the test reference by email when I book the test from Portugal?

Many thanks in advance!