Health insurance BIK v drawings calculator

Have a client who took out health insurance a few months ago, paid for by Ltd co (her & son are shareholders). 3 policies for her (a director), her son (a director), son's wife (an employee). Is there an easy/quick way of calculating whether it is better if it stays as a company expense, goes on P11d (don't currently need them) & pay Class 1a NIC (both directors 40% tax payers) or if payments go through directors' loan accounts (both in credit).

Thanks