Question about Tube Circle Line

You would just go to Notting Hill Gate Station and take the Circle Line via Victoria 3 stops to South Kensington.

The CityMapper will give you all the options for any journey.

You could go to Paddington and get the Circle Line via Victoria but I suspect that would take longer.

The way the Circle line works now is that trains start at Edgeware Road then run via Notting Hill Gate, Victoria, Liverpool Street, Euston and Paddington in an anti clockwise direction to Hammersmith (H and C station). Starting from Hammersmith (H and C) they do the same loop clockwise ending at Edgeware Road (but having gone through Edgeware Road once before heading towards Euston- 6 minutes after Westbourne Park!).
So the trains don't split. You could get on at Notting Hill Gate and stay on the train for 58 minutes as it goes round the loop to Westbourne Park or vice versa.
To confuse things further a few very early and very late circle line trains continue or start in service to or from Ealing Broadway or Barking (both on the District Line) for their depots. Very few people see those trains, even fewer use them.
Or you could get on at Westbourne Park and stay on for the 47 minute ride to South Kensington. However changing at Edgeware Road to go in the opposite direction will be faster (23 minutes + waiting time at Edgeware Road), boarding at Notting Hill Gate onto a Hammersmith bound train even faster (6 minutes).

for almost all its length, the Circle Line shares tracks and stations with at least one other line, so you need to be aware which train it is when it comes into the station.

From Hammersmith clockwise all the way along the top part of the circle and around as far as Liverpool Street there is also the Hammersmith and City. They are joined at Baker Street by the Metropolitan Line as far as Aldgate.

Only the Circle Line makes the short connection between Aldgate and Tower Hill, but no fear, here comes the District Line to go with it all the way to South Kensington and Gloucester Road. The Circle Line makes the corner on its own but is joined again at the next stop, High Street Kensington by another different District Line which stays with it to Paddington and the end of the line at Edgware (again).

The same in reverse.

Thank you for your replies. Yes, I was aware I could go to the Notting Hill Gate station instead, but that means either a longer walk than to Westbourne, or a short walk and take the bus, which of course adds more to our traveling cost, plus you have to factor in the time waiting for the bus.

Besides CityMapper have you uploaded
https://tfl.gov.uk/.

At least you are close to the Lock and Lantern.

Since you mention the Hammersmith station for the Circle and Hammersmith lines, I have another question. It appears from reading online that that station is not connected underground with the Hammersmith station for the District and Picadilly lines, Doe that mean you have to exit the station, cross the street and enter the new station, thereby being charged for two separate trips?

I ask this because we are planning trips to Syon House, Osterly Park, and even possibly Strawberry Hill, and it seem like going from Westbourne to Hammersmith and transferring is the shortest route, instead of Notting Hill Gate to Earl's Court.

The bus is another way to South Kensington- take the #70 from Westbourne Park Road or Cherston Road- it terminates at South Kensington Station- timetabled as a 28 minute journey.

I'm looking at the old paper map of Central London buses, then the PDF timetable for the route to double check. You never see the full printed timetables for London bus routes on the street, but they do exist.

The 70 is a single deck London bus, not a double decker. For a double decker take the 328 from Westbourne Park to Brompton Road, changing to the 430. This is a hopper journey, as the change is inside 62 minutes, so a single £1.75 fare.
The C1 also does the last stretch (White City to Victoria) but that is also a single deck route.

Correct about the two Hammersmith stations being a cross street change, but they count as what is called an 'Out of Station Interchange'. So as long as you don't go shopping in Hammersmith on the way between platforms it counts as a single journey.

There are very many OSI's around the system. There is a time limit for each OSI, 20 minutes in this case.

For general reference this is the full list- https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fcontent.tfl.gov.uk%2Fout-of-station-interchanges.ods&wdOrigin=BROWSELINK

I wasn't actually specifically trying to get to the South Kensington station - I was just using it as an example for wanting to go anti-clockwise on the circle line, since that will likely be a trip we would be making multiple times considering the areas we would want to go to. Going clockwise all the way around is clearly not efficient because of the large amount of time required. Bottom line is that we will most likely need to get to eth Notting Hill Gate station when wanting to go in that direction.

Bottom line is that we will most likely need to get to eth Notting Hill Gate station when wanting to go in that direction.

Just to make it clear, there are three different circle line trains that serve Edgeware Road.
1) One train where the next stop is Baker St
2) One train where the next 3 stops are Paddington, Bayswater, Notting Hill Gate, etc
3) One train where the next 3 stops are Paddington, Royal Oak, and Westbourne Park

If you want to take the circle line from Westbourne Park to South Kensington, you would simply travel 3 stops on either the Circle Line or Hammersmith and City Line to Edgeware Road. At Edgeware Road, you would change to a different circle line train (via Paddington, Bayswater, Notting Hill Gate, etc.) to South Kensington. You don’t have to walk to Notting Hill Gate but depending on where you are staying, it may be faster to walk to Notting Hill Gate.

Thanks for the clarification - I got myself confused. I do have to wonder if going to Edgeware, getting off to switch and then head back but towards Notting Hill Gate will actually be faster than just going to Notting Hill Gate. Google tells me it will be about 10 minutes via walk and bus, or about a 15 minute walk by itself from our flat to Notting Hill Gate. In contrast, it is only a 5 minute walk to Westbourne Park.

Of course it will all depend on how often the bus or tube is running and how much they are running on time. We may just have to experiment.

while we are down the rabbit hole, can we ditch the "e"?

Edgware only has one, at the beginning. Same for the station, same for the locality in northwest London, same for the main shopping road connecting the two.

If you want two "e"s, there is an Edgeware in New Zealand ... but because of being so far south everything is upside down and they land on their heads when they jump....

;-}

I do have to wonder if going to Edgware, getting off to switch and then head back but towards Notting Hill Gate will actually be faster than just going to Notting Hill Gate.

Even if you were starting out right at Westbourne Park station it would generally be longer to take the underground via Edgware Road to Notting Hill Gate than taking the bus, or for that matter walking.

The 28 and 328 buses each run on a 10 minute frequency, so on average there should be a bus every 5 minutes from Westbourne Park to Notting Hill Gate station.