@Catchrene
I have worked around Sidcup for a few years. It seems ok. Not exactly a hub of excitement, but ok. When you say that you are looking to live somewhere as “as a black couple” what exactly are you meaning, or looking for ? It is quite a predominantly white area. That doesn’t mean that you will necessarily feel isolated. But if you want somewhere that is multicultural, then Sidcup may not be the top of your list.
If you want safety, I have always felt safe, walking around, even at night.
If you want somewhere that is easy to drive to/from, the traffic in Sidcup is a pain. There are always traffic jams at peak times. I think that it is due to the high number of schools in the area. During school holidays, the traffic is great.
I don’t have kids, but, from the number of school kids that seem to come to the area (and the cars that their parents drive!) I assume that there are some good schools there. As you only mention that you are a couple, I assume that this is not currently on your list of priorities.
If you want somewhere that is accessible to other areas, then Sidcup is actually quite good, public transport-wise. It is a short journey into London and other hubs.
If you want good food, I quite enjoy the numerous restaurants in the area. There is a good variety of decent places.
If you want a decent place to have a drink, I think that Sidcup is found wanting in this area. There is a lack of anywhere decent. You may wish to go somewhere else for that. In which case, the train may be your best option.
If you want to go for a walk, there are a small number of places that you could go. Google maps is your friend, there.
To summarise, it is quite a nice area. A few standard chain shops on the high street. Safe to walk around. Not necessarily cheap to buy. Fairly green. Decent restaurants (but can get a great curry). Nice, but a bit bland.
Hope that helps