In fact much of our "Sovereign Parliament's" time is spent rubber stamping EU directives, laws, rules and regulations onto to statute book. It was estimated by the House of Commons Library that approximately 60% of parliament's time is spent this way.
Now that might be your idea of a Sovereign Parliament, but it sure as hell isn't mine!
Our elected MEP's, the UK government, and the HMG Appointed Commissioners are involved in every step of every EU law. These laws don't get to the point of 'being rubber stamped' until/unless HMG agrees to them. The idea that we are rubber stamping laws into the UK statute book with no say in the process is bogus.
However, even once the laws have been agreed, and entered into the EU rulebook, Parliament is still sovereign. It can vote to obey the the laws it has previously agreed to, or it can vote to scrap the whole lot and leave the EU. What it cannot do is pick and choose which laws it wants to obey, and which it wants to ignore. That's been the leave camps problem all along - they think they can have tariff free trade with the EU, tariff free trade with the rest of the world, and no freedom of EU movement, and no EU financial contribution.
Whilst we are in the EU there is nothing to stop us 'just saying no'. No additional money, no Euro, no EU army, no loss of rebates, no new EU laws, etc. But once we leave, we lose all that, and chances are we'll have to follow any new rules they dream up without having a say in any of it.