2. If you are short on animal manure for your allotment, think about sowing a green manure such as mustard which can be dug or rotavated into the soil later in the year or next Spring.
3. Make "a re-cycled items list" of useful gardening items you ran out of this year. Examples, plastic bottles and other containers, bits of string for plant ties, jam jars, egg boxes for chitting potatoes. Etc etc.
4. September is probably the prime month to be stung by wasps. At this time of year wasps start to feed on fermenting/over ripe fruit so be wary of drunken wasps.
5. Sow some of the following crops in September. Spring onions, radish, Winter hardy onion white lisbon, Spring cabbages, Japanese onions. Autumn onion sets, garlic.