raising ground height to create paved area

My garden is split level.  The upper part has been created by building decking on to a frame.  I would like to replace this area partly because the timber is rotten and also because foxes have a habit of building their dens underneath it.  I would also like to replace it with something more solid and enduring  ie. paving - what is the best way to raise the ground level to form a basis for paving at the required height (18 inches or so).  I'm also a bit stuck as to what to do then with the surrounding beds - will I also have to raise them?  I would be really grateful for your advice or any suggestions.