Thing to sow undercover from July

Barring accidents, I'm assuming the GH might be erected by mid July at the latest.  The border soil is ok but not brilliant and improving it will be a work in progress.  I've more than enough beans, cucumbers, courgettes  and tomatoes.  What bright ideas have you all got for me to sow/plant in July to make me feel the new GH is mildly productive.  I could sow now in modules if necessary but haven't got a potting place (it's full of tomatoes and cucumbers )
I'm thinking maybe some carrots to last into the late autumn.