Here are some links that you should read about zero hour contracts:

https://www.waronwant.org/SportsDirectShame?_ga=2.24667706.1663227016.1551880541-440177916.1551880541

https://www.clactonandfrintongazette.co.uk/news/national/17304231.labour-gig-economy-workers-trapped-in-dickensian-conditions/

https://www.theguardian.com/commentisfree/2018/may/24/deliveroo-couriers-dystopia-union

https://www.independent.co.uk/news/business/comment/zero-hours-contracts-insecure-work-taylor-review-employment-jobs-a8318586.html

https://www.independent.co.uk/news/business/news/gig-economy-zero-hours-workers-two-jobs-same-time-zurich-study-a8112851.html

https://www.theweek.co.uk/zero-hours-contracts/58853/mcdonalds-offers-all-staff-an-end-to-zero-hours-contracts