You haven't explained why the de-scope is happening which does have a bearing on the answer, non-the-less the clause 34.1 instruction is a compensation event under clause 60.1(4) unless the reason for it was the Contractor's fault. Provided the works that have been stopped are on the critical path then you are entitled to include prelim type costs in your compensation event quotation for the delay. Since you don't know if / when you will be instructed to re-start work the PM should state an assumption about this under clause 61.6 which allows you to quote with some certainty.
If the PM fails instruct the Contractor to restart within 13 weeks the Contractor may terminate provided it was not at fault in the first place. However if, prior to termination the Employer awards the work to another contractor this may indeed be seen as a repudiatory breach however your remedy is the same, termination for R19 at clause 91.6 which in addition to other amounts entitles you to recover the direct fee percentage on the work that was de-scoped.
If the PM fails instruct the Contractor to restart within 13 weeks the Contractor may terminate provided it was not at fault in the first place. However if, prior to termination the Employer awards the work to another contractor this may indeed be seen as a repudiatory breach however your remedy is the same, termination for R19 at clause 91.6 which in addition to other amounts entitles you to recover the direct fee percentage on the work that was de-scoped.