I don't understand, how can you get so little?
The standard loan for someone living in London away from home is £4988. If you're not going to London, the standard loan living away from home is £3564.
I go to a London university, I pay £93 a week and the standard rent time is 32 weeks. So that would leave me with £2012 left over from my maintenance loan, which would technically be £62 a week spending money but there are one off costs in the first term (like accommodation deposit, kitchen equipment, books) to consider so it's more like £40 a week. Which would be okay for me, but I also work as a private tutor - one hour a week [although in reality it's more than that because you have to prepare for lessons] for £15. £55 a week is comfortable for me even with £10-15 spent on London travel every week - but then I have always been frugal.
Maybe this is partly because I didn't get into halls for first year so had to find a private rent, which worked out cheaper. My second year friends at universities outside London tend to pay £60 rent and £10 a month bills (ish).
I do think it is mean that anyone has to work long hours in part time jobs during term time. You're there to study and should be able to do so.