As regards the request received to notify ALL working hours for that week. The Agency are obligated by the Regulations to obtain and retain this information for a period of two years.
If you fail to comply, then I would suggest that they would have grounds to withhold payment.
The next point is as to whether you were driving under EC Rules. I.e. Driving under Domestic Rules is exempt from WTD and only comes into effect if during any 17 week reference period, if you work more than 10 days under EC Rules. And remember that the current reference period ends on 31 July 2005, when calculating any subsequent working under EC Rules.
In fact, the Agency, to comply with their obligations, should have already requested details of ALL work completed since 28 March, together with any sickness and holiday days taken.
As for the matter of the damage. Don’t worry about it. Everybody makes mistakes and if everyone, employers and agencies alike, failed to ‘invest’ in new blood, then the system would soon grind to a halt. Look at it this way, having done it once, you ain’t ever likely to do it again. 
Whoever ends up paying, they all know that people involved in Transport tend to swap and change for no other reason than they are bored or someone else is offering a few pennies more. To an Agency, YOU are a potential “Cash-Cow”. If they don’t find you work, then they don’t make a profit. Even if you leave and get a full time job, who will it be that you will look to first for any additional days, or in periods between jobs? Obviously any Agency that has supported you and treated you well. Mishaps are inevitable during the early months, even years. It is a risk that is factored into the structure of businesses.
As to whether ‘shunting’ is a good way to learn. I have mixed feelings on this.
If EVERYONE is aware of a lack of experience on the part of the person, and a full safety briefing has been given, together with watchful supervision during the initial hours, and the person is allowed to work at their own pace, then yes it is certainly beneficial.
But if everyone is expecting everything to be done at the same speed as when regular staff are undertaking the function, then it is a recipe for disaster.