@FiveMoreMinutesPlease in terms of actual figures we topped up to maximum maintenance loan from minimum loan, minus accommodation cost of £6.3k self catered and then divided what was left over the 30 weeks he would be away. That meant just over £100 per week.
Ds is doing a course with no materials required, ie no books to purchase. He spends around £35 on a supermarket shop tops up maybe bread and milk in the week. Laundry is around £3.80 per wash, tumble drying was free in first year and £1.80ish this year. Circuit laundry, pretty standard in uni accommodation. He probably buys a take away once a fortnight if that, he prefers cooking and he gets more value for money. He is in private halls of residence for both second and third year which costs more than first year halls. We still give him £100 per week for 30 weeks.
That leaves money for travel, he comes home once a semester so every 5 weeks ish and he got a young persons railcard free with his student bank account which sees a cost reduction. He and his mates tend not to socialise in a pub as drinks cost way too much. Ds uses his left over money to pay for going out over the holidays, camping with mates, a couple of gigs etc. He always has money left over because he is a saver.
Consider what you may want to cover or expect them to cover such as phone contract (£10 for Ds he is on our family plan) Netflix, Amazon, Spotify, clothing, shoes etc. Don't forget the initial outlay for their room such as duvet, pillow, towels, kitchen stuff and a laptop possibly. I hope that helps.