I didn't set my Sky email up till last October, as i was still using my O2 one, but i changed my password etc... anyway, just in case, although saying that, it wouldn't make a difference now anyway, as the hack was 2yrs ago, so they've already got your details.
The issue with Sky email is complicated in that the login details are (for a first Sky email account) shared with the Sky website login. In theory if they managed to crack the password they could also access your Sky account details. The hackers may or may not realise this.
I do have a sky email account but it is effectively unused and I never login via the webmail portal. I doubt there is anything there of interest to a hacker. But there is so little known about this particular hack, and the media has been putting out wild speculation, that I am not going to lose any sleep over it - as said, it happened eighteen months ago and the roof hasn't collapsed yet.