It is not currently possibly to use an ATG Tickets voucher on LOVEtheatre.com The vouchers are not interchangeable and must be used on the corresponding websites.
For West End Shows, ATG vouchers can be used to purchase tickets for The Ambassadors, Apollo Victoria, Duke of York's, Fortune, Harold Pinter, Lyceum, Phoenix, Piccadilly, Playhouse (Kit Kat Club), and Savoy theatres.