What are the legalities of a parent allowing their child to have an underage party on the premises?

I am a 16 year old girl and next month is my 17th birthday. I have been unsuccessful in hiring a venue for my birthday as they have strict rules and regulations on the age of the people having the party. So I'm trying to convince my mum to let me have a party at home. The only problem is my mum is a childminder and she is worried she will lose her licence as obviously it's a teenage party, most of the teens are going to be drinking or worse. So for theoretically what would happen for instance if cannabis was found being smoked on the premises by a person at the party or someone was drunk enough to injure themselves? Would it make a difference if my mum was "aware" of the party happening or not? If you could think of any other cirstances that would be helpful in your answer please feel free to include them.