Next month my boyfriend is coming to work in the UK on a Tier 5 sportsperson visa sponsored by his employer. However he wants to come as a tourist before his work visa starts. From Argentina, he is a non-visa national so can stay up to six months as a tourist without a visa.

Can he enter the UK and get his visa stamped at the border and then have his work visa processed whilst still in the UK, or does he have to go back to Argentina to re-enter on his work visa?

Also, does he have to have his return ticket booked? Because he is technically allowed to stay 6 months as a visitor but his work visa is for 1 year, if possible he won't book a return journey yet since for more than a year’s time.