Hmm I think translating that faithfully will need a bit more context. But usually you can just say ตอนที่อยู่ในเมืองจะไปตัดผมด้วย translating to ‘whilst in town

Hmm I think translating that faithfully will need a bit more context. But usually you can just say ตอนที่อยู่ในเมืองจะไปตัดผมด้วย translating to ‘whilst in town (will) go cut hair also’. The ‘จะ / will’ is a universal word that can be added to other verbs to signify ‘future in due course’.