at our airfield (UK) we say one of two things;
If we want you to join the visual circuit - "Go Around...." "Join Rwy xx, not above 1000 feet QNH" Though if the GA is anticipated before hand over to Twr, the Director will say "in the event of a missed approach, turn L/R into the visual circuit, not above 1000 feet QNH"
"Execute Missed Approach Procedure" and send them back to Director who will pick them up for another radar vectored pattern.
MM