Measuring voltage

Hi. I want to measure the voltage of a circuit and how capacitors or extra loads affect it etc. I believe i need an oscilloscope for this so i can see the line going up and down and how flat it is etc.

Can anyone recommend a good cheap oscilloscope? Im more concerned about cheap than good actually. I just want something to give me a good idea, i dont need absolute perfect precision. I hear you can get one for your PC thats cheaper than a proper one. Has anyone seen those?

BTW, im from the UK so it would be best if someone knows a place in the UK that sells them. Rapid do but they are in the hundreds

Ive just been thinking about an oscilloscope again and i found one in Rapid. Its not exactly cheap but ive decided i want a good one now.

http://www.rapidonline.com/Tools-Fas...lloscope/76999

I dont see anything in the specs about the max voltage you can measure with it but on the picture it says 30Vp Max under each socket. Is that 30V? Ive never seen "Vp" before and google isnt finding anything on it