Class A drugs, carry the greatest penalties, they are either drugs that have no medical use, such as Ecstasy or drugs that are being used IV. They also contain 'Medical Drugs', not used by the person prescribed and might be sold to a third party.
Class B drugs, are not as serious as Class A, but still carry penalties that can affect you, these now include many synthetic cannabinoids and cathinones, like mephedrone. Prescribed medications like codeine and 'Dance Drugs' like Ketamine.
Class C carry the least penalties, still up to 2 years in prison. This group contains Benzodiazepines and GHB, GBL and Khat.
'Legal' is by far the most difficult term to explain, as in reality it means 'controlled', this can be by age and licence, alcohol and by licences. Under no circumstances should legal ever equal safe. Alcohol and Tobacco are by far the greatest killers and alcohol in particular causes major social and economic costs to society.
So 'Legal' never will mean that you can grow and produce a substance and give it to anyone, it means a controlled regulated system with age, playing a major part in this.
Ask Chemical Bob
We have produced a legal statement which is important, we are not in any way advising that you use drugs without the guidance of a medical professional and that you are aware of the units for alcohol and are aware of the dangers of purchasing products on-line and are aware of the General Medical Officers advice around Tobacco and the advice from the Chief Medical Officers around Alcohol in pregnancy.