A hypothetical element in the name Gódhel, a late Sindarin replacement for Ódhel “Elf who left for Aman”, but Tolkien said “it seems most probable that it took g- from the old clan-name Golodh, pl. Goelydh, which it practically replaced” (WJ/364). Thus ✱go- “away” < ✶wā- is probably a false etymology.
Neo-Sindarin: For purposes of Neo-Sindarin, I would use gwa- as the prefix for “away”, as in gwahae “✱far away”.
The Sindarin suffix go- “together” was established early in Tolkien’s life. It was derived from √WO and had a variant gwa- depending on ancient patterns of stress, since ancient wo > wa > gwa when stressed but when unstressed wo > gwo > go (WJ/367-368). The go-variant is the normal form, and gwa- survived only in a few two-syllable words such as gwanon “twin = ✱together-born”.
Conceptual Development: The go-/gwa- variation dates all the way back to the Gnomish Lexicon of the 1910s, but in that document the primitive form was ᴱ✶ŋu̯a which become go- when unstressed (GL/40). The derivation of N. go- from ᴹ√WŌ was introduced in The Etymologies of the 1930s which when stressed produced gwa-, but this gwa-variant was already limited to old formations in the 1930s (Ety/WŌ).