Also try
Holiday Extras. They have the Hilton but also the Sofitel which is usually a bit cheaper but just as nice. It is connected to the North terminal so you just catch the shuttle to the South Terminal for Virgin Flights. It runs very 3 mins and tkaes less than 5!
HTH
Elise
BTW We got it ofr next September for £173 including 15 days meet & greet parking