Until the UK has private healthcare and enough rich people to pay for whatever elective treatment they want, this isnt going to happen here.
Many trans organisations like Mermaids have wanted this option available. It’s only the sensibilities of people noticing their attempts that have prevented the lower age of this occurring in the UK on the NHS. WPATH, a lobby group other countries pay far too much attention to, say it should happen at any age.
Puberty blockers are a completely different ball game. The justification for their use is to DELAY decisions being made. Contrary to the OPs anxiety about decisions being made for children. But that bit of logic wouldn't suit your agenda would it?
Puberty blockers are a treatment. 99% of children who start them progress onto wrong sex hormones. Their use is not about “delay” or “time to think”, it’s Stage 1 of the treatment pathway. Wrong sex hormones is stage 2. Double mastectomy is stage 3.