I didn't see anyone hit the car. (not from above) I thought it was someone banging on the window.
A few things don't add up:
How did she and affair man know where George lived? (Maybe she had his details through work)
Why did Mr X get access to the house where George was simply by ringing the bell? Who did he say he was?
Why is Mr X pretending he is Intelligence or similar? She ought to know that anyone who really IS in intelligence is given an alias/ fictitious job like 'I work in a boring job in IT'. They don't imply they are in intelligence at all!
On another note, is the guy who played the 'advisor' telling her what her options are, the same actor who is a cop in current series of Silent Witness? (That had me really confused!)