How do I make use of a greenhouse in summer

[Cloud]

We now have a greenhouse that came with the house, but its entirely empty. We've never had a greenhouse before. It's end of July and every thing I read about assumes we planted crops in the spring. Is there any useful thing I can grow now to make use of this space.

I'm also worried that when I away for a week (early August) anything I plant today will die before I get back, so maybe I need to wait until mid-August before planing.

The greenhouse also has a few cracked panes. I was going to fix these with gaffer tape to make them safe. Should I be thinking of any other maintenance jobs to do in the greenhouse or with the soil?

[Odsox]

If you like salads then you could grow winter lettuce and winter hardy spring onions.
Lettuce needs to be sown in September and planted out in mid-October and onions can be sown in situ at the same time.

Spring cabbage would benefit from some protection and heart up earlier than outdoor ones.
Seed for that can be sown outside between now and mid August in any old plot and transplanted when big enough.

Both those crops would be over and done with in time for tomatoes or whatever next spring.
For the border soil, I would just dig it over and maybe dig in quite a quantity of chicken manure pellets, and then give the soil a good soaking, that way you might well find loads of weeds germinating which you can then deal with before planting your wanted veg.

[ina]

I work for a veg producer, and the polytunnel is in constant use... Last week for example - early beetroot out, fennel in. As soon as one thing comes out, the next goes in. So there's plenty you could still do. But the week away is a real problem - you can't afford that with a greenhouse/polytunnel, unless you have somebody to look after it for that time! One sunny day, and your crops have had it.