Let's take your scenario over the course of 2 years (the time your DS took to save up for a house)
Assume 2 weeks off per year for holiday where normal expenses do not apply, but I have added on the cost of the holiday
Coffee and a sandwich 5 days a week (£5 x 100 = £500)
A new iPhone 5S 32GB (£290 on a £31 contract = £1034)
Weekly clothes shop (£50 x 100= £5000)
Weekly nails (£25 x 100 = £2500)
Monthly haircut with highlights (£100 x 24 = £2400)
Weekly meal out at a restaurant (£30 x 200 = £6000)
Pub drinks twice a week (£20 x 200 = £4000)
Nice holiday once a year (£1000 x 2 = £2000)
Total cost over 2 years: £23,434
Total cost of a 1 bed flat just outside London: £200,000
It still doesn't add up. Even with this ridiculously extravagant lifestyle (which nobody on here actually leads) you still would need to save up for a very long time to buy a house.