Cabin crew can certainly be a good place to be to make contacts, and it can be valuable experience. You should also look at dispatch, ramp work and operations as other possible contact-making opportunities.
Several ex-Virgin CC have made the transition to the flight deck with other airlines, and the contacts they've made within VS have often been able to help with introductions and so forth.
However, the pay's rubbish and it's bloody hard and generally thankless work, so be sure you're ready for what you're letting yourself in for!
Scroggs