I have developed an online exercise generator which allows you to quickly generate English grammar exercises in the moodle quiz format as well as in the hot potatoes format. Just enter the sentences in a simplified syntax and get a complete exercise including feedback for various typical mistakes.
You can find more information and the code here:
The program itself is hosted here:
It makes use of learner data collected over a long period of time. Feel free to use it - and to comment on it. I'm not claiming it's perfect but maybe it's some help and a good start.
Thanks very much for that Christian. It certainly does look easy to use! I look forward to trying it.