Can a bailiff turn up to property with a friend or spouse if they stay sat in the car?

Yes

Bailiffs may take other people onto the premises named in the enforcement power.^[1]

They may assist the bailiff,^[2] but they must not remain on the premises without the bailiff.^[3]

^{[1] Paragraph 27(1) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[2] Paragraph 27(2) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[3] Paragraph 27(3) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007}