My impression was that the House of Lords and the House of Commons function like our Congress. Am I wrong?

That, in essence, the House of Lords, while they cant make new laws, can essentially Veto anything the House of Commons sends to them. Yes, they may not abuse the power for whatever reason, but what would stop them from doing so? What could the British masses do about it if they chose to use it?

Does Britain have the equivilant of a Constitution? In Spain the masses have control of the Constitution, which supercedes the king. So the monarchy has absolute authority except when it conflicts with the constitution...which is controlled by the masses. So while not technically a democracy in name, it is the same end result.

How is the judicial branch elected in Britain? By popular vote or by appointment from elected officials?