There is already the case with the trans man/woman using a fake penis with the lights off, I do wonder though if a fake bio-vagina from surgery will be treated differently though
The law in the UK treats surgically constructed penises and Vagina's no differently from the non artificial ones.
There has been case law on this subject
from an English Court from 1996 onwards and is explicitly mentioned in
some more recent sexual offences legislation.
Sexual Offences Act 2003 S.79(3) said:
(3) References to a part of the body include references to a part surgically constructed (in particular, through gender reassignment surgery).
Hence a trans man (with a surgical construction approximating a penis) could legally rape another person and a trans woman (with a surgical construction approximating a vagina) could themselves be 'vaginally' raped as far as the law is concerned.
What the law does say is that you cant 1) misrepresent the act itself or 2) pretend to be a specific other person known personally to the complainant
For 2) this would include sneaking into a bed at night and pretending to be the partner of the occupant and having penetrative sex with then with yout penis (surgically constructed or otherwise)
A classic case where this could happen is with identical male twins.... if the 'other' twin sneaked into his brothers bed and had sex with his brothers partner the fact that the partner consented 'at the time' would be negated as they thought they were consenting to sex with a specific person (their partner)
NOTE: this is different from telling someone that you are an astronaut, race driver, millionaire etc to get someone else to have sex with you as the deceit needs to be the pretence that you are a specific person the victim would consent to have sex with not that you have lied about your own status or character.
For 1) to be applicable (in a scenario potentially applicable to a trans person) the deceit would need to be something like using a sex toy in place of a penis.
Because the act itself has been mis represented (the victim consented to penetration with a penis not anything else in its place).
As per my above citations the law already treats surgically constructed genitalia no differently from the analogous 'natural' body parts so you could not (under UK law) be prosecuted for not mentioning that your penis or vagina is surgically constructed and you were born with genitals that dont match you current appearance.
I think the Trans activist, Sophie Cook, is referencing cases where a 'pre op' trans person would have to disclose their status and could be prosecuted if they misrepresented the act itself....Like was the case with the aforementioned pre op trans man who used a prosthetic in place of what was expected.
The relevant part of English law that covers the two sections I mention above is
S.76(2) of the Sexual Offences Act 2003
(2)The circumstances are that—
(a)the defendant intentionally deceived the complainant as to the nature or purpose of the relevant act;
(b)the defendant intentionally induced the complainant to consent to the relevant act by impersonating a person known personally to the complainant.