So yeah, it is great to have an income as a student, particularly in London. I wouldn't be able to pay my rent otherwise, the student loan is totally insufficient for even rent alone, let alone other expenses on top of that. But there is a major downside as well.
Back on topic, it depends what year are you in. If youre going for an internship between 2nd and 3rd year (and you should), you can easily spend most of 1st and 2nd year socialising and intern/3rd working hard and still get a solid 1st degree
If you meant excluding rent and bills, say they cost £15/day (which is still unrealistically cheap), plus your £1 for living expenses, that's a monthly cost of £480. Per academic year, that costs about £3840. While this is well within the threshold of the maximum student maintenance loan, remember you'll still have to pay travel costs (you can't really stay within walking distance of your house for the entire time you're in London), buy books (which can get very expensive), pay for other materials for coursework. At a minimum. University, and living in London generally is very expensive...
Mostly, I'm just thinking, how do you even eat on £1 a day? That's pretty much one tin of baked beans plus a slice or two of bread per day. Or maybe some rice. Luckily nobody has to pay medical costs here...
Also, I'm interested as to whether or not you think a gap year internship is still really important if I'm already working? I've had two jobs so far, that's quite a lot of experience for someone who's only in second year, and a lot more than many graduates I know...
plus youll earn some money which you can spend in the 3rd year (typical intern pay for programmers is £15-20k)
and yeah that was without the bills. i lived in houses close to uni to avoid commuting and the £400 was common if not a bit steep, but i suppose my uni wasnt in central (it was brunel in uxbridge). also i lived in pretty shitty houses, because hey, im only there for a year, but on the upside met lots of cool people.
a key to eating cheap is buying in bulk and cooking large amounts of food. say you buy 10 or even 20kg bag of rice (i used to do it on indian holidays for better discounts), that will cost less than £10 and last a few good months. get some canned veg, maybe micne. big tescos in poorer areas are your friend. its hard to calculate but for around £7 (and certainly for £10) you can stir up enough to last you a week. shits not gonna be gourmet but it works.
there are other ways too... freeganism, putting stuff through self checkout as onions, etc.