Just want to give anyone a heads up if they are NOT a British citizen but a British resident. I showed the my American passport during embarkation and the person was very confused. I showed her my official 'indefinite leave to remain' and she didn't have any idea what it was. She left to speak to her supervisor which took 10 minutes. Therefore, make sure you bring something to confirm your residency.
Also, my husband has 2 middle names. This confused the person again. Seems the computer didn't like that and couldn't put his information in. She had to go back to her supervisor. This took another 10 minutes.
Make sure you screen shot everything. There is NO Wifi connection and I saw loads of people having difficulties. A couple actually showed their NHS cards as proof of vaccination because they couldn't get the NHS app to work.