There are no direct flights to Siwa during the winter. The two options in the winter are from: Cairo (which means you can see the pyramids) and Alexandria. If you are planning to visit Siwa in the summer, there are now direct flights into Marsa Matruh from Manchester and London Gatwick. For details of these flights visit Marsa Matruh flights section.
BMI, BA and Egypt Air all fly direct from the UK and are the easiest ways of getting to Cairo. BMI flies to Cairo and has the best prices, arrival and departure times. Flights leave from Heathrow at 09:05, arriving in Cairo at 15.50. The return flight leaves Cairo at 14.40 and arrives in the UK at 19.50 every day and costs around £278 including all airport tax. Here is a direct link to BMI’s web site. Air Italia and several others have cheaper options that have stop over’s in Europe on their way to Cairo.
For the more adventurous who want to travel as cheaply as possible (this is what we do) catch an Easyjet flight to Munich from Stanstead and then fly direct to Cairo on a TutFly flight. If you book these flights well in advance you can get a return for £125.
British Airways no longer flies to Borg el Al Airport. Alexandria can be the best option if you are not planning on visiting the pyramids. There are cheaper routes through Italian airlines around £250 – £300 return with direct connections or short stop-overs in Italy.