Haven’t bought flights online for ages.

Looking for some flights to Vienna for 2x adults, 1x 9yr old. Birmingham is closest airport, going in August this year for a week.

What sites should I check?

I tend to use fly.com

But do check all the prices from a London airport, with better selection it might not be dearer & you have more choice for flexibility

skyscanner and kayak here

Depending on how much of a cheapskate you are, you can also look at flying into Bratislava, which is closeby.

normally I look at the airport I’m going to and check the schedule to see who flies there and from where – good guide as to who to look for. Failing that one of the check everything sites (sky scanner etc.)

I use opodo.co.uk
I normally go at least once a month (albeit from Manchester) but that’s where I get the best deal.
It’s quite expensive to go from Bratislava to Vienna.