You can ONLY setup VM from the handset (you have to dial 222). So, either you burn up the minutes, or just wait till you get to UK where it will be free. (VM access is free in UK).
Here:
http://www.virginmobile.com/mobile/user_gu...mail_guide.html
Phones: Xiaomi Mi Mix 2, Samsung Galaxy A50, ASUS zenfone 3,
Sim cards: AT&T (Contract), 3 UK, Piranha Mobile