I’ve read about another similar challenge online: save £1 on Monday, £2 on Tuesday… and so on until Sunday, when you put aside £7. Rinse and repeat every week or just put aside £28 at the end of the week and by the end of the year you should end up with ~ £1450 
If you’re serious and committed about this, you can create a new pot and set it to unlock only at the end of the year! Now that’s a proper challenge! 