Firstly, most gardeners suggest that you don't even bother starting a garden bed until you've flattened the soil. This is especially important if you're going to build a tall garden bed. There are going to be a few visible height discrepancies in the bed if you haven't flattened the ground first.
Secondly, consider the amount of rain you have each year and the wood you'll be using for the garden bed. Wood eventually rots from too much water, even if you paint it with a protective coat of paint. Many gardeners prefer using natural looking stones or brick for their garden beds for this specific reason.
Lastly, keep in mind that you don't want to install a raised garden bed if you're going to be moving soon. This is a long-term investment in your garden, both financially and in regard to the time and effort you'll put in to create this, and building it just to leave your home after a year makes little sense.