Representatives of the Sizewell area took little comfort from a “fact-finding” trip to the site of another power station planned for Somerset.

Members of parish and town councils surrounding the nuclear site near Leiston, returned from Hinkley Point with more questions for developers than when they left.

The Sizewell Parishes Liaison Group (SPLG) called plans to house construction workers “totally unsustainable” compared to the Hinkley Point C project – also being developed by EDF Energy and already given government approval.

It also raised fresh concerns about congestion on the A12, the environment and tourism.

But EDF Energy, which facilitated the visit, organised by West Somerset councillor Chris Morgan, said Sizewell C was at a much earlier stage than Hinkley Point C, and that whatever worked well for one site might not suit the other. It said the preferred location for non-home based workers was “likely, but not definite”.

The SPLG also thought that education and employment benefits seemed more realistic for Hinkley, due to the presence of large science-based colleges.

The group said that the land in Hinkley was of poorer agricultural value, and that the workforce requiring accommodation was half that of Sizewell.

While Hinkley Point C will accommodate 500 workers next to the construction site, with two brownfield sites in Bridgwater housing the remaining 1,000 workers and a total of 650 parking spaces, proposals for Sizewell C involve a single site for 3,000 workers on the edge of what the SPLG described as a comparatively tiny village of Eastbridge – a four kilometre bus ride from the construction site.

As for transport, the group noted: “Congestion on the A12 will be unavoidable, with worker traffic and HGVs from north and south – and without a Sizewell relief road, the B1122 will clearly not be adequate.”

On the environment and tourism, it said: “Although Hinkley Point C has some wildlife and habitat issues, the areas affected by the build are not as environmentally sensitive as in Suffolk, nor as highly protected by European designations.

“Tourism is a major industry in Suffolk, especially on the Heritage Coast. This is not the case at Hinkley, although some concern was expressed that holidaymakers approaching Somerset may be deflected from the area by the heavy traffic on the M5.”

In a report written following the visit, the SPLG concluded that EDF had “a larger site to play with at Hinkley” – not “cramped” by the proximity of woodland, protected areas of outstanding natural beauty (AONB) and sites of special scientific interest (SSSI) – and that the nearest communities had smaller populations than those around Sizewell.

EDF Energy said preliminary works at Hinkley were already well advanced, with a design approved by UK regulators and a nuclear site licence in place.

A spokeswoman said: “It does not necessarily follow that initiatives and developments which work for the local area in Hinkley would work for Sizewell, so we continue engagement with local residents and look forward to launching stage two public consultation on our proposals later this year.

“As our project team gather more information from our investigative studies on key areas such as the environment, accommodation and transport strategy, we have shared this at the Sizewell C community forum. For example, at the community forum in November we said that the development site for non-home based workers is the likely but not definite location for this facility.

“We understand the concerns of the immediate local community and we need to work together to address these concerns just as we also have to listen to the feedback from all respondents to stage one.”