Hello Annie,
I'm really only familiar with flights to Corfu leaving from Glasgow and Newcastle so I really cannot advise you on the airports of your choice.
I know that for myself
www.xl.com offer the best fares from N'castle/Glas, the flight times are not always great, but I like the prices!
You will find that they fly from your preferred airports Birmingham and East Mids.
I know that I mentioned it earlier elsewhere, but when doing a search online at XL type 'Telegraph' into the special offers box to gain another £15 discount each.
The longer you can hang on the lower the prices. At XL you can search online for a maximum of 9 adults & 9 children, therefore if it shows availability you know that there are at least 18 seats. I did this all week when waiting on the prices dropping, but when they went down so low today I decided to go for it. If the availability was not there for 18 passengers then I would have had to make the decision to book earlier at the dearer price. Maybe this is too much hassle for some people, but it does mean that you can get at least a couple of breaks a year for the price of one.
Take a look at their website to get an idea of their late availabililty/prices from your airports this weekend.
Eileen.