We went first day of school holidays last year and paid £420 with Delta and then another $79 each way to upgrade to economy comfort which was definitely worth it. Checked Virgin this morning for 6th to 29th August and they want £1325 each! In 2012 I paid £800 on Virgin going the day the Olympics started and that was premium economy both ways.
One thing that gives me comfort is that last year I checked Virgin prices a week before we went and they obviously hadn't sold all their seat because economy had come down to £700 for our dates. Not sure my nerves would take waiting that long though.
I have been checking the seat situation on the Delta flights (same routes as last year) and only about 3 seats in economy showing booked. When I booked last year, seats were allocated as soon as I booked and I could change for free so I am assuming, wrongly or rightly that not many seats have been sold. Therefore I do expect the price to drop from around the £900 mark on Delta.
Also, for the last 2 years my friends and family have booked US Airways in March for school holidays at £600. I am hoping that this will happen again this year. The both went on the LHR to Charlotte then MCO route and both had good experiences.
All else fails I'll just have to pay the £800 or so to go indirect, wont like it but better than not going. Luckily we are a little flexible and can go for a max of 25 days.