Astra won't start-all dashboard lights flicker?

Sounds like it is just a flat battery. It may just need removed and recharged.
Could he have left any lights on by mistake? Even leaving an indicator on will flatten the battery as, on the vauxhalls, this will leave a parking light on with the key removed.
A warning beeper should sound if you open the door with any exterior light on but he may not have heard it, or not realised its significance.
Other common causes of flat battery are faulty boot switch or boot not closed properly leaving boot light on, interior light left on, incorrectly fitted hands free kit or charger, non standard sound system etc.
It is also possible the alternator is not charging the battery properly while driving or that the battery has failed and is no longer able to hold the charge.
All these things are easy to check.
Did you buy the car from a dealer? If so try phoning them for advice, they may be willing to help on a goodwill or warranty basis, or at least at a reduced cost, as long as you dont immediately start accusing them of ripping your dad off!!

If you're anywhere near Perth, Scotland I'll have a look myself!

Brian
October 2009