Catrin - suggestion for you; go rent a mountain bike and go with someone who has a little experience; My suggestion is ask Tanya, she helps instruct at the Midwest MB Womens clinic. She is very nice and willing to help a girl out which is awesome.

If I were you I would go full suspension. It's sooooo much easier on the body. Yes it is heavier but personally I would rather have the more comfortable ride. IMO.