If a criminal steals your data or causes damage to your computers you should report the crime to the police. There’s no difference between that and a physical break in or theft and it’s nothing to be ashamed of.
Action Fraud is the UK’s national fraud and cyber crime reporting centre. You can report cyber crime via their online reporting tool http://www.actionfraud.police.uk/report_fraud
If you are suffering a live cyber attack that is in progress, call Action Fraud now on 0300 123 2040 to report, do not report using the Action Fraud online tool. This service is available 24 hours a day, 7 days a week for businesses, charities and organisations.
Depending on the type of attack you’ve suffered it may be appropriate to contact the police after you have completed the process of identifying the attack type.
The more incidents that are reported to the police the greater their levels of intelligence will become. This will enable them to provide practical advice founded on real experience of attacks, which means a greater chance of the criminals being thwarted.