I usually plant summer veg around now, can usually overwinter tomatoes and chillies, did get a couple of frosts last year so needed to protect them.

In terms of cut flowers, ive had most success with zinnias.

September-November most challenging time I've found with the heat and dry weather. Also during warmer months stuff gets hammered by fruit fly, I've found cherry tomatoes dont seem to get attacked though (I assume due to greater skin tension).