You will not have a frozen ATPL. You have a MPL which means you will need to have 1500 hours first before you getting your ATPL. This is not that bad because everyone of us need first 1500 hours before getting our ATPL. You will not have the same benefits and priviliges as a CPL and/or Instrument Rating holder. I don't know exactly what kind of privileges you will have you will need to look it up with EASA.