Elizabeth Line changes Nov 6

Great news, so, I can go all the way from Heathrow to Stratford without a change but I need to get on the right train correct? Then at Stratford, I would need to change for Braintree or Witham. That would make things so much easier for me.

Margaret

It appears only to be the next stage and not the final service pattern
From what i can see trains will only be running from Heathrow to Abbey Wood
Perhaps Nigel will correct me or tell you what your best route after the November changes

I'm happy to be proven wrong. Every day is a school day, after all.

I'll quote parts of two paragraphs from my source:

However from November 6, trains will start running through the new
central section to Reading and Heathrow in the west (beyond
Paddington) and Shenfield in the east (beyond Whitechapel, using a new
tunnel to Stratford and then taking over the existing route via
Romford).

...

With Bond Street station opening prior to the new timetable too,
Paddington, Bond Street, Farringdon, Liverpool Street and Whitechapel
will get 16 trains per hour off-peak and 22 trains per hour in the
peaks. As the trains coming from Paddington will have to serve both
branches to Abbey Wood and Shenfield, instead of just Abbey Wood at
present, Canary Wharf, Custom House, Woolwich and Abbey Wood will
actually get fewer trains - just eight per hour off-peak and 10 in the
peaks (a train every 7.5 minutes off-peak and every 6 minutes peak,
meaning an increase of maximum waiting times of 50 per cent off-peak
and 20 per cent in the peaks compared with the current service).

The full service is not due to start to May 2023
Trains from Shenfield will only go as far as Paddington from November

and clarified from a different source:

This means that customers travelling from Reading and Heathrow will be
able to travel east all the way to Abbey Wood without changing at
Paddington. Customers travelling from Shenfield will be able to travel
west all the way to Paddington without changing at Liverpool Street.
Journeys to onward destinations, including to Heathrow Airport or
towards Reading, can be made by changing trains on the same platform
at any of the central London stations.

Yay! 45 years after Paris, London gets its own proper RER 😂.

(I am teasing, obviously. The London Underground and the existing railways did a much better job of serving Greater London than their Paris equivalents, so I guess it wasn't as urgent).