Yes oddly the plan diagram does show any intermediate stations between Bristol and Cardiff, nor Cardiff and Swansea, but this can't be the planned stopping pattern (or lack of one).
You seem to have different planned diagrams. The
DfT» IEP▸ diagrams spreadsheet I have shows the Neath, Port Talbot Pwy and Bridgend stops.
Didcotdean is referring to the 'Proposed Weekday Class 800/801 Service Pattern' as show in the
Government Response to 2014 Great Western franchise consultation (on page 38) which shows the service pattern that
FGW▸ intends to run after the complete introduction of the IEP fleet in December 2018.
As didcotdean says, there are a number of intermediate stations, including Chippenham and Bath Spa towards Bristol, and Newport, Neath, Port Talbot Parkway and Bridgend towards Cardiff and Swansea, which do not appear on this diagram.
There are a few differences between this calling pattern and the one the DfT had been proposing in the peak and off peak. For those which have not seen this the core service pattern is as follows:
Off peak pattern
1tph to Bristol Temple Meads calling at Reading, Swindon, Chippenham and Bath Spa with certain hour extensions to Weston Super Mare and Exeter St Davids.
1tph to Bristol Temple Meads calling at Reading, Didcot Parkway, Swindon, Chippenham and Bath Spa.
2tph to Bristol Temple Meads only calling at Bristol Parkway.
1tph to Cardiff Central calling at Didcot Parkway, Swindon, Bristol Parkway and Newport.
1tph to Swansea calling at Reading, Swindon, Bristol Parkway, Newport, Cardiff Central, Neath, Port Talbot Parkway and Bridgend with certain hour extensions to Camarthen.
1tph to Cheltenham Spa calling at Reading, Didcot Parkway, Swindon, Kemble, Stroud, Stonehouse and Gloucester.
1tph to Worcester Shrub Hill calling at Reading, Oxford and stations to Worcester with certain hour extensions to Hereford.
Peak pattern & variations
1tph to Bristol Temple Meads calling at Reading, Swindon, Chippenham and Bath Spa with certain hour extensions to Weston Super Mare and Exeter St Davids.
1tph to Bristol Temple Meads calling at Reading, Didcot Parkway, Swindon, Chippenham and Bath Spa.
1tph to Bristol Temple Meads calling at Chippenham and Bath Spa (calls assumed as these stations are not shown).
1tph to Cardiff Central calling at Bristol Parkway and Newport.
1tph to Cardiff Central calling at Didcot Parkway, Swindon, Bristol Parkway and Newport.
1tph to Swansea calling at Reading, Swindon, Bristol Parkway, Newport, Cardiff Central, Neath, Port Talbot Parkway and Bridgend with certain hour extensions to Camarthen.
1tph to Cheltenham Spa calling at Reading, Didcot Parkway, Swindon, Kemble, Stroud, Stonehouse and Gloucester.
1tph to Worcester Shrub Hill calling at Reading, Oxford and stations to Worcester with certain hour extensions to Hereford.
1tph to Worcester Shrub Hill calling at Didcot Parkway, Oxford and stations to Worcester.
The main differences between this pattern and the one previously stated by the DfT off peak is that the Swansea service now additionally calls at Swindon and Bristol Parkway, the Cardiff services now skips Reading running non-stop to Didcot Parkway, and services extended to Weston Super Mare from Bristol are now the one via Chippenham and Bath. In the peak the 2 tph that run via Bristol Parkway to Bristol instead has one running to Cardiff Central running non-stop between London and Bristol Parkway. The other runs via Chippenham and Bath to Bristol in the peak, not calling at any stations between Paddington and Chippenham. Also in the peak an additional service is shown running to Worcester, giving stations between Oxford and Worcester 2tph in the peak, and runs non-stop between London and Didcot Parkway.
The use of the term "certain hours only" is interesting for the extensions of services to Hereford, Weston Super Mare, Exeter St Davids and Camarthen, as this doesn't give as clear a frequency that these stations will be served. This particularly applies to Western Super Mare which in the DfTs pattern was going to be served hourly from London, and Hereford that the DfTs pattern showed as being served 2 hourly from London.