Also book thru a cashback site Quidco or Rpoints will give you 3% cashback,
This is from my Rpoints statement
Virgin Holidays £2,759.40 - £82.78 Rebate
I booked back in Dec for Next Xmas, then they had the 15% New Year sale, when I checked they had put the price up to discount, I would have been about £100 worse off waiting for the sale. Always find the same for Virgin.