JFC, the UK government wouldn't be paying. Your airline are responsible for shipping you back if you are denied entry at the destination. Hence it's in their interest to check you aren't very likely to be denied entry. If you don't believe it google it:
https://travel.stackexchange.com/a/100806
This is the type of stupid hyperbole that gives Ralph wins. No one said the UK was going to deport him. If he gets denied entry he never entered the UK and it's up to whoever shipped him to the airport to sort it out. Deportation would require ralph to have been admitted entry to the UK. If he is denied entry and refuses to go home Tom Hanks style then the UK would have to issue him temporary entry for the purposes of removal.
Customs is after immigration. If you get to customs then you have been granted entry already. If you get to customs and they find something they don't like then they can arrest you and deport you.
Do you guys even have a passport or did you just watch a video of one on youtube?