I may have to defend my GC position

Always fight for what you are for, not what you are against.

So state you think women and girls deserve to retain their hard won rights and protections. Say that girls deserve to compete with their own sex and undress with their own sex. Challenge those who disagree, why do they want girls and women to lose privacy? Why do they want anti scientific lobby groups in schools?

Freedom of religion is also important for atheists. If somebody tries to force you to pretend to believe in the trans religion they are breaching your rights.

Why not fight your battles when you get to them?

I think you have to start with the ideology rather than get into all the implications, and keep it as simple and irrefutable as possible.

"I have some concerns about linking sex to personality traits under the label of 'gender identity'... Much of the work of feminism has been to dispel the belief that your sex determines your personality and interests, and we should be careful not to suggest to children that this regressive, sexist equation is true in reverse: that their personality and interests determine their sex. How do we ensure a supportive environment for kids who identify as trans, as well as all the others, without reinforcing outdated, offensive stereotypes about what it means to be a girl or a boy / a woman or a man?"

I'm in a really similar position, JellySlice. If you can get hold of the book edited by Michele Moore and Heather Brunskell-Evans it might be helpful - I found the final chapter, by Michele, really good in helping me get my head round how to make the case. I have the following three-part argument ready to hand - three clear points tends to be all that will stay in my head!

1. Male and female are distinct biological categories about which children need to learn (someone upthread said this, and I agree, it's top of my list too). Gender is socially constructed and not innate - you can bring the faith aspect into this if you can stay on track, but I tend not to because it takes me off in a tangent.

2. Gender dysphoria amongst pre-pubescent and early-pubescent children is not that uncommon, but with 'watchful waiting' (NHS phrase) around 80% grow out of it. If those 80% are put onto puberty blockers or other kinds of medical interventions prematurely we risk harming their bodies (the long-term effects of medicalising children this young are still not fully known) and their minds (it will become much harder for them to backtrack if they're already undergoing interventions, and the peer group pressure to stay transitioned is huge).

3. There's no such thing as a 'transgender child'. There are children who experience discomfort with aspects of their gender, see above, but rather than medicalise them, we would do better to address the conditions that create such discomfort. So address gender stereotyping and gender-typical expectations, and low-level homophobic abuse. We currently have a situation in which society around children is sexist and homophobic, and gender-atypical and lesbian/gay identities are still stigmatised. Transgender identities on the other hand are glamourised (especially online), making them attractive to those children who don't fit the gender typical pattern (many of whom are on the autism spectrum and have a range of reasons for not fitting in, and find the idea of their rainbow family existing out there very attractive). So let's address the problem at source, and do what we can to loosen up those gendered and other expectations that leave some children feeling like misfits.

Good luck!

I go off on tangents myself so I know what you mean. I tend to stick to - there are only two sexes. Because there really are. If anyone says there are more than two then I would invite them to name them. Of course they can’t.
Yes defo bring up the faith aspect. Freedom to believe or not believe is very important.

4thWaveNow is "A community of parents & others concerned about the medicalization of gender-atypical youth and rapid-onset gender dysphoria (ROGD)"

They've put together tons of information. For instance:

4thwavenow.com/2017/09/08/suicide-or-transition-the-only-options-for-gender-dysphoric-kids/

TransgenderTrend website will likely be good source of information as your focus is young people:
www.transgendertrend.com/about_us/

long interview with Stephanie Davies Arai:

Guardian article May 2018 describes differences in approach:
www.theguardian.com/education/2018/may/15/transgender-row-teachers-afraid-challenge-breast-binding

Claire Graham discusses differences between Allsorts/ Mermaids school toolkit and Transgender Trend's specifically from a policy, legislation and Safeguarding perspective:

Be very clear that gender non conforming behaviour is fine; people should be free to express themselves within the body they have. Damaging healthy bodies, removing fertility and committing to a lifetime medication and unknown side effects has to be a last resort.

I keep reading on twitter that gender critical is anti gender non conforming. Dispel this myth!

Discussion about useful 'fact-check' document with linked sources:
www.mumsnet.com/Talk/womens_rights/3448982-Trans-Fact-Checker

Threads with resources:
www.mumsnet.com/Talk/womens_rights/3145470-Break-it-down-for-me

www.mumsnet.com/Talk/womens_rights/3335962-Frequently-Asked-Questions-FAQs-I-have-noticed-here

Recent article by Assoc Professor Michael Biggs (Oxford) which discusses misuse of sucide statistics by Mermaids etc in context of ITV drama 'Butterfly' (reference to GIDS)
www.transgendertrend.com/suicide-by-trans-identified-children-in-england-and-wales/

Useful article by James Kirkup with embedded links:
blogs.spectator.co.uk/2018/05/why-are-some-mps-trying-to-shut-down-the-transgender-debate/

Surely point 1 should be science; male and female are biological sex classes. Children need to know which one they belong to; girls need to learn about menstruation and pregnancy.

That gives you a neat one sentence answer which is a strong, dependable position, and naturally leads on to point 2; safeguarding.

Point 3 is a list of the various problems with transitioning. Meds are being used off label in a way that sterilises gay and non gender conforming children. Its gay eugenics.
The reasons they are being used this way are based on faulty statistics. The risk of suicide is being vastly inflated, the risks of transitioning are being underplayed.
80% of 'trans' children desist and come to terms with their sexuality.

I think all the relevant stats are on the Fair Play website.

Would there be an opportunity to arrange a viewing of Michele Moore's video? If you get tongue-tied it could help you? Or invite in a speaker or organisation?