A friend of mine, presumably with poor opsec, ordered 100g of MDMA from NL to UK; The police simply knocked on her door, arrested her and then seized her laptop and phone. She's on bail until March, and due to her situation, young, in education and work with no priors, will most likely get a short suspended sentence.
This is a warning however, LE in the UK don't fuck about, denying ownership of the package isn't gonna stop them seizing your electronics so maintain proper opsec. Use TAILS, don't mention your purchases over SMS or any IM service, encrypt your laptop and phone if you have to.
She will have been arrested on suspicion of having committed an offense, whether she gets charged with anything will depend on if they find anything else or if she admits to anything. If they don't find anything else she will get a letter saying no further action will be taken.