TLDR: I'm in the UK and trying to come off up to 100mg Diazepam (Valium) per day. What are my best options?

I've suffered debilitating anxiety my whole life. The type of anxiety that used to stop me being able to work, socialise, etc.
I discovered Diazepam (Valium) about 2yrs ago while in the USA. We were going to a gig and I was having a panic attack, and somebody gave me one and it worked fantastically - had a great night without any anxiety and was actually able to enjoy a social night out for once.
It's the only medication I've tried that has made me able to live a normal life. I've now got a full-time job which I'm excelling at and love, I have the confidence to meet new people, etc (as I'm sure you guys know, anxiety can make one very lonely, leading to depression).
My tolerance has increased over the last couple of years and I've also been taking Xanax at times (therapeutically, like the Diazepam) when I've ran out of Diazepam (I've been buying from the clearweb, and the pills may be underdosed - the majority have been Galenika Bensedin 10mg).
I'm now at the point of taking 50mg of Diazepam in the morning, and 50mg after work to help me sleep. I know I'm going down a very dangerous path and would like to stop safely. What are my options?

Do I go and see my GP and just be completely honest? Can they report me to the law, etc? (I'm an adult). My GP is very nice regarding my anxiety and prescribes me 3x40mg Propranolol per day. She actually sounds like she cares. Can a GP put me on a prescribed taper?

Should I just stop cold turkey and go to A&E when the inevitable excruciating WDs kick in? (I've tried to stop CT before and couldn't last long). Will they just give me a small dose to tide me over and kick me out?

Do I seek out a Drug Treatment service? I know I'll need to be prescribed (hopefully) more Diazepam in order to taper safely, but I'm not sure a Drug Treatment service can prescribe Benzodiazepines?
I just desperately want to stop this nasty habit - it makes me feel ashamed and like a criminal, and I know it's dangerous for my health (I'm mid 30s/M/healthy BMI/don't drink alcohol at all/work out 3x per week/clock around 10,00 steps a day at work/eat relatively healthily).
The only other things I take are Propranolol, Ambien on occasion, and an espresso and an energy drink during the day (the Diazepam is starting to make me slow, and my job involves a lot of manual labour and alertness).
Please can anyone tell me the best route to getting off 100mg Diazepam per day?
I'm definitely committed to coming off it -- I can already see the negative effects it's having on my life -- I just don't know where to start.
Any experience/advice is greatly appreciated.