Yup you need to strip the door card off. It's all pretty easy and nothing scary. You then need to undo about 8 bolts that hold the mechanism into the dor and the glass to the mechanisim. 5 mins of wriggling it about will have it all out of the door. Refitting is the reverse of removal (he he).
When you buy a replacement make sure you get the right one. I bought one and the guy asked what year.I said 87 and ended up with the mech for a Golf with quarter lights that mine doesn't have. Which ever one you need shouldn't set you back more than £15 including VAT and not take more than an hour of your life to change.
Good luck,
Nick