The ukash "virus" is not actually a virus. It's just a scam website that makes it look like your browser is locked up.
Go to Settings -> Clear Cookies and Data. This will prevent Safari from trying to open that page and will solve the problem. No other measures are necessary. There is no need to fear that your Apple ID has been compromised based on this, fortunately.
If this happens again, take note of the page you were visiting when this appeared, and don't go back there. Either it's a bad site, or it has been hacked.