A person could easily get the impression the UK didn't police crime online, simply because crimes like DDOS attacks, cryptolockers, cryptocurrency scams, identity theft, fake tech support callers and suchlike are all typically cross-border crimes where the police have basically no powers.
The reality is the police are more than happy to act when the criminals involved can be identified, and are under their jurisdiction, and you can get the attention of the right department - that's just a very rare set of circumstances.
The UK police do have powers though, accessing computer systems without permission or committing fraud is a crime in the UK regardless of geographic location under the Computer Misuse Act 1990.
The Act explicitly mentions prosecution of offences committed abroad.
It's just really hard to do anything useful when the perpetrators, even if identifiable, are never going to set foot in the UK nor any country which has an extradition treaty with it.
The reality is the police are more than happy to act when the criminals involved can be identified, and are under their jurisdiction, and you can get the attention of the right department - that's just a very rare set of circumstances.