I live in Cardiff so I can offer some advise. Other than school fees, I suppose rent would be your next biggest expense.
If you are planning to study at Cardiff University, your best options are to live in Cathays or Roath area. They are within walking distance to the university (10 - 20 minutes at most). I used to cycle to uni, even nowadays I cycle to work as parking in the city is quite expensive. Student accommodation should cost around £200 - £240 depending on size of rooms and facilities. Broadband, gas, electricity and water are usually all inclusive. I know of some students living in Riverside and Splott area. They may be cheaper but not as convenient and are not desirable areas to live.
If you live in university residential halls it should cost you about £2600 - 2300+ per academic year. Download this page:

http://www.cf.ac.uk/for/prospective/reside...s%202011-12.pdf

I do mostly home cooking so my cost are very low, say about £20 should easily last me a week. Takeaways can cost you around £4 - 6 per dish but their portions are quite huge!

If you need a car, it is relatively cheap. £500 - 800 should buy you a nice 8 - 10 year old Fiesta or Micra. Insurance is a killer and can easily set you back £500 at the very least. You can use your international license for a year. Travel by bus is around £1.25 onwards. If you get a return, you can use the same ticket the whole day. Train is expensive. A trip to London and back is about £72. I use Megabus. Booking online in advance cost a mere £1 all the way to London!

I suspect cost of living in Glasgow is pretty similar. Personally I prefer Cardiff for its relatively better weather, nice friendly people and lovely city. Glasgow is rather gray and gloomy and the city has seen better days. Good luck!