What to plant in September

I have two wooden planters, approx 6 foot long and 3 foot wide. 

One has some tomatoes that have succesfully grown outside (in Scotland - woohoo). I have taken a dozen or so already and expect to be picking the rest of them over the next couple of weeks.

The other planter is empty. So I have on  ready to go now and one in approx 2 weeks time once the tomatoes are done.

Both planters are in a south facing garden, but quite windy.

I don't want lettuce, but anything other suggestions for this time of year would be appreciated.