Can I create a TIN from contours lines (shp) in QGIS?

I need to do a slope analysis, and would like to make a TIN from 2m contours lines. Or do a slope analysis directly from contours? The only DEM available is not precise enough. I do not have any elevation raster files.

And how do I then make slope classes? The TIN properties does not seem to be able to classify anything other than elevation.