Well, I'm not familiar with OLBA, but I looked at the charts.
The VOR DME 16 has straight in minima of 800 ft and circling minima of 1070 ft.The MAP is D3 KAD. There would be nothing wrong with maintaining 1070' until 3DME (= aprox. 1,2 NM before the RWY 16 threshold. ) At D3 KAD, whatever altitude you are at, you MUST start the missed approach.
The charts says that circling is only allowed W and N of AD and only to RWY 03/21, so executing a 'circle to land' to join right hand downwind for rwy 16 over the sea would be illegal.
BUT..., I would think that if, during the missed approach procedure you see the airport, and you request and obtain clearance to perform a visual approach (Don't call it 'circle to land') via right hand downwind over the sea, THAT would be legal.
Easa requires a 800 m RVR for visual approaches, and you must be able to keep visual separation from terrain. (It's not a legal requirement to have the rwy in sight at all times.)
So, yes, I would think it's LEGAL to perform a 'visual approach'. Would it be wise and safe to do it if you wouldn't have the rwy in sight at 800' during a straight in approach?
That's an other question? I wouldn't be trying it, but maybe, just maybe, somebody who is thoroughly familiar with the airport and the obstacles around it could do it safely.