If you are looking for a cost effective way of learning to fly (I wont say cheep!) I would second the suggestion about trying gliding, especially as UCL have such a strong gliding club. Take a look at their web site
Welcome to the UCLU Gliding Club
To give you an Idea, when I was at university in the early 90's I went solo in 50 winch launches and I did this in about a year. I could easily have done it in less time if i had gone flying more frequently. At UCL this would cost you £40 membership, £4.50 per launch and 10p per minute soaring fees for flights over 10 minutes. You could be flying solo for under £300 - now I will use the word cheep!
If you go on to get your bronze badge and cross country endorsement you qualify for the gliderpilots licence which you can then convert to an NPPL with only 10 hours additional training. I am not sure if you can count a GPL towards a JAA PPL but I am sure someone here will be able to tell you!
Gliding does require a lot of time. The costs are kept down because club members work together to help everyone else get in the air. You will be expected to do your share and there will be a lot of waiting around. This is not for everyone, however, I found that being immersed in the gliding environment helped me to learn a lot by talking to other club members and instructors and by watching and talking to other students.
You may not have thought of gliding but the controlls of a glider are exactly the same as a simple powered aircraft (Exept the engine, obviously!) and you will learn how to fly an aircraft. These skills will not be wasted!
It realy might be worth a try!
David