Minting Money

The new pound coin comes out tomorrow, all edgy and as anyone who was alive to hear the sound of a doddlebug will tell you, it looks exactly like the old threepenny piece.
According to the British Mint, there are approximatly 1,553 million £1 coins in circulation so i naively assumed that they will make 1,553 million of the new ones and phase them in as they phase the old round ones out but for some reason i am unable to fathom, they are unleashing 1.5 billion of the new ones.
Now i never said i was a mathematical genius or know anything about economics but if i am reading it right, they are taking out £1.5 million and putting back in £1.5 billion which seems a bit wrong to my mind.
If the government can just conjure up money out of nowhere and throw it into the financial system, why the decade long austerity cuts?
There can only be a certain amount of money available as that is how some people get rich by accumulating it and the only way of changing that would be to create more money out of thin air to spread amongst society.
There are more people in the UK now than there were 100 years ago and there seems to be more money too, so did the Government at some time just decide to physically make more of it and if they did, how did they decide it and why can't they just create even more money to make us all even wealthier?
When the Capitalist system goes all recessionary again, as it obviously will, and we need to bail out the banks with hundreds of billions of pounds again, why not just mint a couple of hundred billion of pound coins and use that instead?
There must be a reason why no one seems to have thought of it sooner but if we are just about to unleash over an extra billion pound into the system, someone must be benefiting from getting the extra money that wasn't there before tomorrow so why not us so we can end this awful Conservative Party led austerity drive?