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I am not sure, but I don't know if a pre assessment simride makes you feel better during your selection simride for the uk airline (tfly?)
they don't want to see a rated 737 pilot. You don't have to meet the type rating requirements.. They want you to show them your capability to learn from your mistakes. They want to see if you are trainable and if you can take some critisisme. They want to see some basic skills, not specific 737 skills!
goodluck