There is some framing going on with talk of 'the surrender bill' beyond the more obvious one in the term 'surrender'. To be clear:

A Bill is not an Act of Parliament. A Bill becomes an Act if it is approved by the House of Commons and the House of Lords, and is formally agreed to by the reigning monarch (known as the Royal Assent). An Act of Parliament is a law, enforced in all areas of the UK where it is applicable. (www.parliament.uk)


The difference is that a bill is a proposed law that has not been passed yet, and a law has been passed as an Act.

So it is no longer 'a bill'. It is an act of Parliament. But calling it 'a bill' is intended to avoid drawing attention to the fact it is now law, and to go against it is to break the law.