(I'm not actually familiar with the issue but I imagine if they're "clever" enough to block CTRL+F, they probably also block CTRL+L which is supposed to change the focus to the URL bar. So in the end you have to resolve to using the mouse after all...)

I doubt they care that you’re switching to the address bar, my guess is that most people don’t know the above trick that switching to the browser chrome allows you to get around ctrl+f hijacking.