Hi quinney,
Welcome to the siite get your coat off and pick up a spade. :)
"The two problems with growing the same (or similar) crops in the same area year after year, is that the nutrients in the soil become unbalanced and that pests and diseases which are attracted to the crop can increase in the soil.
By changing the position of the crops, the nutrients can remain balanced (as different groups of crops require different nutrients) in addition soil borne pests and diseases are reduced as they are not given the chance to build up year after year."
After saying all that as Rockets are first early tatties and have a short growing season and as you dont have anywhere else available. You should be ok as long as you dig some compost in when planting them or use a general purpose fertilizer.. Because Your king edwards last year will have took a lot of nutrient out of that plot.
I am sure you will get more input to your question so see what others have to say on it.. cheers Jim...