I haven't checked but from the course I have taken at Warwick, you should normally be able to choose where you want to do a 3 year BSc or a 4 year Masters.

 

BSc would be 3 years, MEng would be 4. Same as anywhere.

Looked at UCAS' website?

 

http://www.cs.ucl.ac.uk/undergraduate.html

Depends on what course your do, 4 year is there, the MSc/MEng I guess, the 3 year being the BSc/Beng.

Just browse the site I just found on www.google.co.uk