As has been said you need to work out what you are doing and advise ATC accordingly.
Are you going to fly an instrument approach to minima and then fly a visual go-around to depart to another field VFR without landing? If so as has been said it would be wiser to follow the standard missed approach (or ATC instructions) and then ask for VFR once established on the missed approach. I'd expect the airport in question to want to charge for this approach.
Are you going to fly an instrument approach to minima and then go around into a visual circuit to land? If so this is a circling approach and should have its own published minima.
I've found that charging for instrument approaches that end in full-stop landings varies depending on the airfield in question. Many airfields will not charge additional instrument approach fees for a non-local aircraft as long as you pay for a full-stop landing.
Busier fields like Biggin reserve the right to charge light aircraft an additional fee for the instrument approach in good VMC (ie. the instrument approach was not really necessary). Other fields will always charge you additionally for the instrument approach.
As has been said, it's best to call to find out. Don't always expect the first person you talk to to know, though - I've been put through to all and sundry at one place to find out whther I would be charged extra for an ILS approach in CAVOK conditions (at Exeter and I wasn't charged - nice friendly airport).
cheers!
foggy.
[ 25 November 2001: Message edited by: foghorn ]