I just got an email from BA saying my outbound flight at the end of Sept to NBO has been canceled. It was an award ticket (with 241 voucher) booked in oct 355 days out. They have given me the option to get a refund or rebook.

I would like to rebook, as my safari accommodation is allowing us to postpone to 2021 and was looking to go in Aug 2021. Obviously I cant rebook yet as flights aren't released yet. 1) How long do I have to make a decision to rebook or get a refund? 2) Even though I booked the return with 241 vouchers I have 2 separate booking references will I be able to rebook/cancel the return even if BA end up flying it? 3) When rebooking does there have to be award availability? I have read posts on here with mixed responses so am a bit confused, I am hoping so as it would have been our first F. Hopefully, BA will maintain the LHR-NBO route and also F but who knows!