planning ahead

Unfortunately there is no good answer to your question. You might even call the sales office of the airlines to see if you can get a group rate. Some groups start as low as 10. There are so many factors affecting pricing that it is impossible to predict the best time. I would start looking now to track the prices. Check farecompare.com and one of the history tracking sites to find the high and low pricing for those flights. I will look it up and add it later to this posting. Good luck.

We have made major summer trips as a family of 5 six times and each time we bought our tickets between six and eight months ahead - much sooner than many people consider conventional wisdom, and after weighing almost every possible combination of dates and routes. Since I continue to track prices for future reference, I know that five out of the six times we got the cheapest fare available at any time for that summer. The one exception was in early 2009 when the worldwide economy teetered on the brink of collapse and fares did get cheaper in March for flights in summer. If you really want to retain the flexibility to get the lowest fare, you may not get to fly direct from SF to London. There are often trade-offs for the cheapest fares and it will be up to you to weigh cost vs convenience. But the short answer is that no one knows when the best time is. But we have had very good luck buying very early, and the old conventional wisdom of waiting until some predictable "sale" period arrives seems to be less and less valid every year.

I'm not very scientific about how I buy plane tix. I start looking when I have decided on my dates, and that is often about 4-6 months in advance. I have been going to Europe in the spring the past few years, so that means I start looking in the fall sometime. When I see a fare that I "can live with," I make my reservation. From SFO, United is my choice of airlines because that's where my frequent flyer miles are. For years, it was possible to reserve a flight that left SFO at about 1pm and arrive at Heathrow around 7am. Last spring my reservation was changed to one with a connection in DC. That didn't work out well as my flight was delayed and I missed my connection and that lead to other problems. Paulette, I think you could start looking now. You could use a website like Kayak to get several choices and prices.

Right now the British Airways "low fare finder" is showing the lowest price for travel from SFO to LHR next July is $1355. But to get that fare you must pair one direct flight with a one-stop flight on the return. It may not get any lower than that; summer is high season and July is the highest of all. You can buy up to 9 seats on the website but for 10 you are in the area of group rates. You might do well to consult a travel agent for that, to get the best price and routing.

Also, if any in your group have miles good on British Airways, I see award seats available on almost every Monday and Tuesday in July, for the outbound flight. Didn't check the return, but it might be worth an inquiry if you have the miles.

Hi I have been tracking airfares for a trip mid April to early June 2013 SYD to FCO and LHR to SYD. It was three weeks ago the airfares dropped by about $150 to $200 usd,whether you want to wait to see if they keep going down more, is the choice we all make. Fare into and out of LHR were always cheaper, but I wanted open jaw.
I'd also suggest going to the the airline websites, and seat guru before buying those tickets. Best of luck.

Paulette, if you are a AAA member, their travel agents can find a group rate for you (a minimum group is usually 10); they've done great booking trips for our college students going on service-learning spring breaks.