In accordance with the
All Weather Operations (JAR-OPS Subpart E)
Your aircraft is Category B, come hell or high water! The Category B classification is based upon the Vat (ie: across threshold and NOT at touchdown as suggested above) being 1.3 times the stalling speed (Vso) or 1.23 times Vs1g at MCLM in the landing configuration. You cannot change that.
With regards to which minimums are applicable: your company needs to operate according to the manufacturers certification speeds and should make use of the procedures and techniques certified by the manufacturer for circling (and other) approaches in order to remain within the bounds of Category B operations. Flying a higher speed however, makes the higher circling minima applicable.
