From the Crown Prosecution Service website:
"The maximum penalty is a level 5 fine
( = �5000). The court must also either endorse the driver's licence with between 3 and 9 penalty points (unless there are 'special reasons' not to do so), or impose disqualification for a fixed period and/or until a driving test has been passed".
http://www.cps.gov.uk/legal/section9/chapter_b .html#35
In practice, 'without due care and attention' usually results in something like a �250 fine + �50 costs + �15 victim compensation scheme payment + between 3 and 6 penalty points.
Chris