...is there a website that makes it pretty easy to hunt for airfares when you have really flexible dates?

I want to get over to London to see the Savage Beauty exhibition at the V&A, unfortunately it's over early August so it's running right through the busy touristy summer season.

I have some flexibility so I am wondering the best resource to look for tickets. I haven't flown internationally in a long time. I usually use Google Flights.