Sorry to hear that Wilfred, just went through the exact same thing as you have except i was playing Normals. Fortunately i was able to reconnect just as my team was surrendering. So didn't get a Leave for the match, but might get reported for it.
The reason I couldn't reconnect, was because the patch is getting downloaded but it isn't applying the patches. Thus after the Champ Select, the client is not allowing us to enter the game.
[slayer-jinx-unamused]
Restarting the client is not making the client recognize that the patch files haven't been applied. So try this.. Restart your computer/laptop. Launch the client. And then it SHOULD start looking for the differences, which will then lead it to applying the patches.. If that doesn't work, go to the settings of the Client and select the repair option. This again should make it look for the differences.
I had just submitted a post a few minutes before you, stating the whole incident in detail. But I think, what I have written here is enough. Hope this helps.
Here's the link:
http://boards.na.leagueoflegends.com/en/c/bug-report/wXnn7mui-crash-patch-68-is-not-being-applied-due-to-which-the-client-is-crashing-after-champ-select