|UDP flood attacks are pretty harmless to a home user. Where they can cause problems is if they are effectivly carried out on a corporate network or a public website. In your case you can probably just ignore (that is assuming your firewall blocked the packets?).|
You can do a reverse IP lookup to see where the packets were sent from, but any attacker worth a grain of salt will spoofs his/her address. Also if they did not spoof they themselves would be flooded with destination unreachable responses.
If this happens again you can configure your router (depending on router type) to not respond with the ICMP Destination Unreachable packet. Generating this response causes a drag on your router and lets the attacker know that you are 'home' and activly working to block his attack.