Items that are prohibited from shipping can be carrier dependent, and country specific. However, it is important to understand that for safety and compliance reasons - if an item is illegal in the UK then it is also prohibited from being shipped domestically or internationally.
There may be possible domestic and international export restrictions on particular items in some countries or even in parts of the same country, whilst not in others. For example; it may be possible to ship Alcohol (Beers, Wines and Spirits) domestically to some, but not all parts of the UK. There are also restrictions that can be applied to your parcels, depending on the amount of alcohol present (% ABV).