VATSIM isn't really a great tool for practising RT, everything said must be taken with a pinch of salt. This is why it's particularly bad for learning bad habits as you must be able to recognise when phraseology is incorrect. Flight simulator and VATSIM are generally terrible for VMC flying anyway, due to VATSIMs main emphasis on IMC procedures and the lack of decent VMC scenery.
I would recommend Pilotedge though, as every controller is a real world air traffic controller. It only covers the West Coast of the US though, so useless for UK students.
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