This is really blowing up and everyone is being wonderful!
Firstly, re: the petition, you need to be a UK citizen to sign. You also need to make sure you check your emails after signing and click the confirmation link, or your signature won't be counted.
I've seen a few people saying that the petition website is akin to a scam/just an appeasement tactic, and that the government basically never acts on anything submitted there. I think this is at least partially true. But it's also a way to exercise our power in a democratic process and we've GOT to take advantage of that for as long as we can. If nothing else, it's a show of force, and that show is more impactful the more signatures the petition has.
It doesn't work in isolation though. This is why I suggested writing to your MP – it's something quick and (relatively) accessible, and there are tools like the Mermaids one to make the process even simpler. To those of you whose MPs are shite – I'm so sorry. It sucks, I know. (My constituency was conservative from its creation up until last year; the mp was a holdout from Thatcher's government and about as effective as mouldy wet-wipe). If you have the mental energy and time to spare though, then it's worth writing anyway. Don't let them think we're happy to let this slide.
On the subject of email templates, I've had this anon with some good advice that I've answered already, but worth sticking here too:
Keeping this list short because things are overwhelming rn, but here's a few orgs I know of + one or two options they provide for ways you can help:
Mermaids – one of (if not the) premier orgs for supporting trans children in the UK. Have a look around their website to see if there's anything you can do – e.g., donate or volunteer.
Trans Kids Deserve Better – another trans youth-focused group. Their 'Support' page is the place to find ways to get involved, ranging from donating to sit-ins to sending Wes Streeting a little coffin as part of their 'kids are dying, Wes' campaign.
TransActual – advocacy work for trans adults. You can work for them, write for them, volunteer, or fundraise when you shop online without needing to reach any deeper into your own funds.
Where to go for support and advice
All the orgs linked above provide advice and information on your rights, accessing healthcare and mental health support.
Some other useful resources are:
TransUnite – find trans support and/or social groups local to you.
Terrence Higgins Trust's trans-specific resources – information on sexual health clinics, charities, GID services, housing support, and more.
Mermaids' helpline – support for young trans people up to 20 years old. This is also a good place to go if you're worried about and/or want to know how to support any young trans people in your life.
Shout – crisis text line. Not trans-specific, but used and trusted by groups like Mermaids for crisis support. They can help direct you to the right resources and talk you through problems in the moment.
The Beaumont Society's support line – all the support services offered by the Beaumont Society, which include counseling, an information hotline, and support groups.
If anyone has any more resources or ways to act, feel free to add on!