I think, in London at least, you might be better to ignore the advice most people give about bees from the rest of the country.
I took off my autumn honey last week, and most colonies have already packed their brood boxes with more... and yet I've seen advice on this forum that people should have started winter feeding Sept/Oct. That was was when I was taking supers of summer honey off. If I paid attention to them I'd miss out of buckets and buckets of (IMO) some of the best tasting honey.
It's best just to see how the weather works out and watch what your bees are doing than setting strict dates that they are supposed to follow, (which might be harder when you're new).
All well and good but it's not just London or the 'sunny south' that is blessed with a late flow. You can't predict what is going to happen or when from year to year. This time last year there was appalling rain and damp, no ivy pollen coming in and no nectar, some hives refused to take any syrup when feeders were placed on the hives in early September.
This year some colonies (from hived swarms) were near starving and so were fed in late August, one hived swarm that had been there for two months and was a week or so earlier on the verge of starving swarmed
again in early September on what, according to the textbooks would appear to be supercedure cells, others were fed for a short while in early September but then something strange happened - a mild spell with flow from the ivy and balsam that is currently filling a super every two to three weeks on some hive, whilst others remain a bit lighter than I'd like. Two hives are currently on their second tray of Apiguard, yet one still fetches in loads of pollen the other, with near identical looking bees fetches in very little pollen.
The answer in future years might be to forget syrup completely, zap the varroa with an approriate treatment at the end of August, slap on empty supers (and then remove them when they don't get used!) and then at the end of October place a huge block or two of fondant on the top of the brood chamber and seal them up for winter - this prescribed regime might work next year and in future years ...but it probably won't
In summary, bees will do whatever they want to do, whenever and often at the most inconvenient moment.