This is what it says on the website:
Our minimum requirements vary according to the fleet we are recruiting for. Candidates should have at least (my italics) 2,500 hours (depending on the aircraft type and nature of previous experience). You should also have either a UK ATPL or JAR licence, the right of abode in the UK and finally, you should be MCC qualified.
This is the link to the application:
Virgin app
Most applicants have more than 2500, for sure, as you would expect when most of them currently possess A330, 340 or B744 experience. But there are plenty with 'only' A320 or B737 time. What have you got to lose by applying?