After a little bit or research I believe that although you have been cleared for a visual approach you will still be operating IFR and therefore should fly the IFR missed approach procedure. To fly a visual circuit as a missed approach procedure may result in a loss of separation on following IFR traffic.
All IFR approaches are visual from the DA/MDA as is a circling approach and all require the IFR missed approach to be flown if you go missed after DA/MDA. I have regularly nominated joining the visual cct as a missed approach procedure at GA airfields but have always specified this in my R/T with ATC.
To summarise, I would recommend that if you are granted a visual approach confirm if IFR is cancelled and check which missed approach procedure ATC expect with a short concise and unambiguous R/T call.
Keep it clear and coordinated and do not clutter the radio.
MM