Careless driving is sometimes also known as driving without due care and attention. You can only be convicted of this offence if the prosecution can prove that your standard of driving was less that what is expected of a careful and competent driver and That you did not show reasonable consideration for other pedestrians and vehicles on the road.
If you have been charged with careless driving then you should expect to receive between 3-9 penalty points and in some circumstances you may receive a driving ban. A careless driving offence will also affect the amount you pay for your insurance.
If you have been charged with careless driving / driving without due care and attention then you should take legal advice as soon as possible.