Same advice as given before: start booking asap, if you find a cheap fare book it.
You can fly from Heathrow on Virgin Atlantic who are starting UK domestic service this month, or you can fly from Gatwick on Easyjet and Flybe. Take into account overall cost and time of getting to the airport and any baggage fees. You can check Cityjet in case they offer flights from London City airport to EDI which would be your nearest airport.

if you click on your name you can find all your old posts.

Your other thread has the info you need

http://www.fodors.com/community/air-travel/easyjet-186381-2.cfm

And like mentioned on that thread, you aren't likely to get ANY discounts into Edinburgh in August. The city literally doubles in size for all the festivals and they all have to get there somehow.

Don't assume that low costs airlines will be cheapest. Check all the airlines who fly to Edinburgh.

And as it's August and hence Festivals, you are unlikely to get a bargain flight.

I'd also point out that train is going to be as quick door to door and you won't be subject to ritual humiliation and assault.

http://www.eastcoast.co.uk/

>>I'd also point out that train is going to be as quick door to door and you won't be subject to ritual humiliation and assault.<<

That was suggested on the other thread too but the OP may not have seen it.

It's one of the most expensive times to go to Edinburgh.... Book soon.

Thanks everyone. I guess I'm getting anxious and forgot I put in a question already. Just didn't want to drive till we got to Scotland but we are staying in Fife to accommodation isn't a worry.