I'd discounted the ILS approach because the Calibrator was working, and as a Duchess it was unlikely to be approaching at the 90kts IAS of my lowly PA28 and I didn't want to be a nuisance. That was mistake 3, in hindsight - if it hadn't been for the Calibrator I would have requested the ILS anyway, or a PAR. I allowed the presence of the Calibrator to change my weather decision - that sort of cloud would usually prompt some sort of instrument approach.
Tim
(PS circuit height is 800ft so there was plenty of height in theory for visual circuits)