Hi Alun,
Your reminded me of when I took a spectra of M81 and M82. Like you I was just interested to see what I could see in spectra of galaxies. My setup is for high resolution spectra, so it is very hard to go faint and I just see a small region of the spectrum. M81 was almost entirely noise, while M82 though noisy did have some interesting features I could investigate.
Below are the spectrum and the view through my guide camera. It turns out I had placed the slit on some known HII regions called regions A and D. This allowed me to do a radial velocity calculation that showed a redshift of about 255 km/s.
It is nice to sometimes take a spectrum of an object without preconceptions. Then you can experience the joy of discovery, even if many others have been there before.
Cheers,
Andy