Is a single channel oscilloscope enough for most purposes?
I agree with the others that two-channels is very convenient at times.  Particularly if there is a separate trigger input (almost like a third channel).

What are your minimum bandwidth requirements?  Do you really need something as fast as the MSO-19?  The DSO-2090 is a 100MS/s, 40 MHz dual channel (plus external trigger) PC-based scope for £139.  You would then have money left over to buy the standalone £30 logic analyzer.