No problem but you asked for facts and they are facts!
The numbers are correct, there is no dispute even from the remain campaign, they like to focus on the £19,500,000,000 that the Leave campaign (stupidly) continuously quote, but the 8,500,000,000 is not disputed. There is arguement that we will have £10,000,000,000 but I prefer to talk to the £8,500,00,00 undisputed figure.
To your point about not being able negotiate withou "freedom of movement". You do not know that, it is not a fact, it's up for grabs. The trade agreements will be negotiated as and when required, again it is not a FACT that we will not be able to negotiate anything that we don't choose to. Just remember the key word here is negotiate... that is also a FACT, we will negotiate. Beyond that is speculation and opinion!