Access to Exeter
Particularly for participants from Japan, it might be best to book flights to/from London Heathrow (LHR), and take either trains or coach services. Trains can be searched for from Trainline (look for the one from London Paddington to Exeter St. Davids) and the coach services are provided by the National Express. Trains usually take about a few hours from London Paddington station (which can be directly reached from LHR via Heathrow Express in about 15 min). The coaches on the other hand directly depart from LHR to the Exeter city center, but will take a little longer, typically about 4 hours.
Access to Exeter city center and workshop venue
Exeter has a cozy city center with lots of shops and restaurants. It can be directly accessed with the National Express buses. If coming by train, most likely they will stop at Exeter St. Davids station, from which it is ~30 minute walk although simply taking a taxi is the easiest.
The workshop will be held at XFI Building, Conference Room 1, on the University of Exeter Streatham Campus. The Streatham Campus is also in walking distance from the city center.
For more information on how to access to the campus, please see this link.