If you don’t fast for any of the days of Ramadan, you’ll be required to pay a charitable form of compensation.
You must pay Fidya for fasts missed out of necessity, that cannot be made up afterwards.
 
When someone cannot fast in Ramadan and can’t make up the lost days afterwards (for example, because of a long-term health condition), then they should pay (fidya) for someone else to be fed.
 
£5 is the amount required to be paid for one missed fast (which cannot be made up afterwards) for each missed fast. 
However, if someone misses all the fasts of Ramadan, they would need to pay £150.