Sugar syrup 2:1 can be fed at the moment using contact or rapid feeder, or bakers fondant (books say later in the season/winter) but having seen a great beek using fondant at this time of year - either fondant or syrup.
They will store the syrup in the frames - so make sure if you do feed with this that they still have enough room for the Queen to lay the winter bees.
If there is a good area of brood, they will stop when the rest is full. Simples, nowhere to put it. Removal of the feed at that stage will allow the emerging brood cells to be re-used for brooding. The later one can feed (and get away with it) the better. Less feed required if there is a late flow, brood nest will be considerably contracted, there will be lots of winter bees in the hive. All a balance and deciding after careful consideration. One can get caught out and have to feed heavily over the winter - not something a bee-farmer wants to be doing!
Last few years feeding might have been delayed to late September or even later. This year - not sure. BP may have seen to that........
I have found that my colonies have provided for themselves the last five years and provided me with a late honey surplus from some.
However, whatever happens this autumn I will not be taking anything more from the bees to extract from now onwards. Any excess, if there is one, will either stay with them, be redistributed to other colonies or just stuck in the freezer until a suitable use comes up.
Spinner is cleaned and ready to be tucked away for the season.
Also forgot to add that drawn comb makes feeding so very much quicker and easier. They will draw fresh comb while the weather is warm enough, but things are a bit slower - and that needs a lot of bees!