I've often thought I would do if put in that situation, and my approach would be:

If they have my family hostage, then I'd go through with the smuggling and have to take my chances. Most people must get through, otherwise they wouldn't be risking so much drug confiscation.

If they didn't have my family, then I'd find out where the British embassy is, go there straight away and tell them everything - they'd keep you safe and get you home.

If they dropped me off at the airport, then I'd find a british pilot, and ask him wtf to do. He'll probably take you off the airport floor and arrange for someone from the embassy to come and collect you.