I've just been trawling through the explanatory notes
www.parliament.scot/-/media/files/legislation/bills/s6-bills/gender-recognition-reform-scotland-bill/introduced/explanatory-notes-accessible.pdf
As far as I can make out, on application:
Applicant must say if they are married and whether they want the marriage to continue or not.
Must include stat dec from the spouse to say they want the marriage to continue, or stat dec from the applicant saying no such declaration is included.
If no spousal stat dec is included, an interim GRC will be issued after the 3 month reflection period.
There is no requirement for registrar general to notify the spouse that an interim GRC has been issued.
Applicant must apply for a full GRC within 6 months of interim GRC being granted. No minimum time limit so they could apply the next day.
Registrar general or sheriff must notify spouse of this application. This may be the first time spouse is made aware.
Full GRC will be granted if applicant has made a stat dec to say they want the marriage to continue, either as part of the original application or at this stage. No requirement for spouse to agree.
Registrar general or sheriff must notify spouse if full GRC is granted.
Issuing of an interim GRC is grounds for divorce.
In cases where spouse has not agreed it continues to be grounds for divorce after a full GRC has been issued.
So yes, the whole thing could happen with the spouse only being notified in the final stages and no time to end the marriage before the contract is changed without consent.