Format an array of strings with a prefix within a length bound

Given the strings

Accrington Stanley 0-2 Wycombe R
Barnet 0-1 Morecambe R
Bury 1-5 Milton Keynes Dons R
Chesterfield 1-1 Chester R
Dag & Red 0-1 Stockport R
Macclesfield 0-1 Bradford R

Combined with a prefix of “DIV2” and an output length of 76, you’d get

DIV2: Accrington Stanley 0-2 Wycombe R; Barnet 0-1 Morecambe R
DIV2: Bury 1-5 Milton Keynes Dons R; Chesterfield 1-1 Chester R
DIV2: Dag & Red 0-1 Stockport R; Macclesfield 0-1 Bradford R