English idioms relating to luck and opportunity.

Fat chance!	The expression fat chance is used to indicate that something is not very likely to happen. "The boss is thinking of me for the job? Fat chance!"
Fall into one's lap	If something good falls into your lap, it happens to you without any effort on your part. "She's not making much effort to find work. Does she think a job will fall into her lap?"
A free ride	Someone who gets a free ride benefits from a collective activity without participating in it. "Only those who share the work can share the benefits - nobody gets a free ride!"
Get a second bite/ two bites at the cherry	This expression means that you get a second opportunity to do or try something. "He was eliminated in the semi-finals but he'll get a second bite at the cherry next year."
Off-chance	If you do something on the off chance, you think there might be a slight possibility of success. "I went into the little supermarket on the off chance that I would find a map."
It's anyone's call	This expression is used when the result of a game, contest or election is difficult to predict. "Who do you think will win?" "It's anyone's call."
Luck of the draw	To refer to something that happens as the luck of the draw means that it is the result of pure chance, with no possibility of choice. "The samples distributed varied in size and value; it was the luck of the draw!"
Take pot luck	If you take pot luck, you accept whatever is available without knowing what it will be like. "We were so hungry we decided to take pot luck and stopped at the first restaurant we saw."
Make hay while the sun shines	This expression is used as an encouragement to take advantage of a good opportunity as long as it lasts. Successful sportsmen are advised to make hay while the sun shines.
Murphy's law	Referring to Murphy's law expresses a sentiment of bad luck and the idea that if anything can go wrong, it will. "We've tried to prepare for every possible incident, but remember Murphy's law ..."
More by accident than (by) design	Something which happens more by accident than (by) design is done without deliberate intention. "I became an interpreter more by accident than design; nobody else could speak the language of the refugees."
Play a waiting game	If you play a waiting game, you deliberately delay taking action and wait for an opportunity to act more effectively later. "The cat kept its eyes on the bird, carefully playing a waiting game."
Push one's luck	If you push your luck, you try to get more than what you have already obtained and risk spoiling the situation. "You've got your father's permission to go to the concert. Don't push your luck by trying to borrow his car!"
That ship has sailed	The expression 'that ship has sailed' means that a particular opportunity has passed by and it's now too late. "Is the offer this open?" "Sorry, that ship has sailed - you missed your chance!"
Sitting pretty	Someone who is sitting pretty is a good or fortunate situation, especially compared to others who are not so lucky. "He sold his shares at a good time so he's now sitting pretty and enjoying life."
Strike gold	If you strike gold, you find exactly what you need: satisfaction, wealth, happiness, etc. "I think she has struck gold this time in her new job. It suits her perfectly!"
Strike (it) lucky	When someone strikes it lucky, they run into good luck. "We had a sunny week in Scotland. We struck it lucky! "
Tomorrow's another day	This expression means that even if everything is not satisfactory at present, there will be opportunity for things to improve. "For the moment you need some rest; tomorrow's another day!"
Touch wood/knock on wood	This humorous expression, based on superstition, is used to avoid bad luck, often while touching something made of wood. "The order will be confirmed shortly - touch wood!"
Vested interest	If you have a vested interest in a situation or event, you expect to benefit or gain an advantage from it. "Tom has a vested interest in Jack's promotion; he hopes to get his job."
Waiting in the wings	If someone is waiting in the wings, they are waiting for an opportunity to take action, especially to replace someone else in their job or position. "There are many young actors waiting in the wings, ready to show their talent."
While the going is good	If you take an action while the going is good, you do something before the situation changes and it becomes impossible. "There's a 50% discount on subscriptions this month. I think I'll subscribe while the going is good."