I was on the Christmas Andalucia trip and went to Alhambra.
We were dropped outside the main entrance, and there is a 400 yd "road" up the actual entrance, this is smooth tarmac, but has a modest upward slope - it may be possible for you to arrange transport for this 400 yds stretch.
I would guess that the "main" tour involved walking around 800/1000 yds; from memory there are no real flights of steps, but lots of areas in the palace with a few steps up & down, and areas where you would have substantial problems if you can only walk very short distances. There were frequent stops while the guide explained something, but nowhere I can recall where you could sit down. The tour is very slow paced, because of the frequent stops to look at things, have them explained etc.
At the end of the tour, we went to the gardens, this involved a further 600/800 yds of walking, but can be omitted easily, and a number of the group took the short cut back to the entrance.
I should add that Alhambra was for me, the one of the highlights of the holiday, but (again to me) if you can only walk 200 yds or so, then it will be very difficult for you.
Our tour director was Claire, and I believe she does many of these holidays. She is really, really helpful, and I'm sure if JY were to contact her on your behalf she would be much better placed than me to advise you.
Hope that helps.
Stuart