@Arranjack The first question .. is Openreach supplied Full Fibre available at your new temporary address? If not you will probably only be able to get a SOGEA broadband service which is FTTC with no phone service as there is now a stop sell on copper phone lines. As you are on Full Fibre you may not have any phone service anyway.
Plusnet do not offer short term temporary contracts so you would have to do two house moves, I don't know the full details but I think you can either pay a fee or start a new contract, knowing Plusnet's billing systems it could get complicated.
It would be a good idea to contact the Customer Options team on 0800 013 2632.
