My growing conditions will be very different from yours, but yes, radishes will require cooler weather (I'm in Georgia, USA). I can only grow radishes if I plant them in the late autumn / early winter.
Beetroot, I don't know if you will be able to form edible roots during summer (others may have opinions). The good news is that the greens are very good. Beetroot and Swiss chard are both varieties of the species Beta vulgaris. [Sorry, no experience growing scallions].
Best of luck! And congratulations on the peas, courgettes and lettuce!