It's not for me to prescribe the response, I am genuinely curious about how close to the line people who dislike Brexit are. Living in the EU, how close are people feeling to saying 'fuck it, let's do it live' and just winging it like the UK is preparing to do?

Personally, if you are interested, I feel like Brexit leaves everyone worse off overall. The UK will continue to implement just as stupid up-tight fear laws and stifle creativity and productivity in exchange for perceived 'safety'. The EU's copyright proposal is bad, but Theresa May's approach to solving the UK's perceived moral and ethnic threats is likely worse.

Does the average American respond to a stupid law by campaigning for secession?

You could be, for example, remember that the UK already had a internet filtering program which forced ISPs to monitor all the content shared by users within the UK, and the UK government was forced to withdraw it because it was incompatible with the EU Charter of fundamental rights. Yes, that same charter that is going to be repelled after the Brexit.