Yes. There are no penalties for paying the loan off early. We calculate interest daily so the shorter time they have the loan, the less they will pay in interest. Note that the loan is not a revolving credit facility.
Any breaches of the loan agreement by the client can result in Novitas calling in the loan. This can include dis-instructing you as their solicitor without agreement from Novitas or failing to follow advice from their solicitor in any material way.