How many dwarf fruit trees?

After my first year on the new allotment I've realised that I can close grow enough veg in succession on the top two thirds of the plot and still have a "left over" area at the bottom to put to good use (in the photo ,this side of the 2 rows of summer raspberries with the black stakes)

The available growing rectangle is approx 10 x 18 feet ,excluding the path alongside the raspberries.
Inspired as much by the Canarian almond blossom as the prospect of fresh fruit I'm thinking about planting some dwarf fruit trees here.The question is how many?
My initial thoughts are a pear,a Victoria plum and a greengage, 6 ft apart with 3 ft at either end.
Oh,and some blueberry bushes in the "gaps"!

Mid February snow - garden and allotment

Almost Wordless Wednesday.
Click on Mid February snow photo album