My toy breed has become anxious the older she has become, and she's now 7.
She was fine as a pup, well socialised, and her first bonfire night was no problem.
Her second bonfire night was a nightmare and any thunder or fireworks now sets her off. We tried a sedative from the vet but it just made her appear drunk, and she was still panicking and jumping up so it was dangerous.
If we are out walking and I accidentally kick a stone she jumps a mile.
She now does not like her evening walk after a single rumble of thunder several weeks ago. She hides when we are getting ready, the pants with her tail down the whole way round. She gets no enjoyment and just pulls for home. We now cannot let her off the lead on the park after she darted for home, miraculously crossing a main road unscathed, and was nearly home before we managed to get hold of her.
She has also started to become anxious in the car and will only settle with her nose out of the window. A recent short  trip down a motorway with the window shut for safety was a tense journey I don't want to repeat!
We tried some 'mothers milk' tablets some time ago but they just made her very thirsty so we stopped them

Any suggestions would be gratefully received, and any experiences of YuCalm would be great.

I think you need to find a decent behaviourist to help you get started on a counterconditioning and desensitisation plan, in person.  Noise phobias generalise really well, as you're finding, and they can be very hard to address once well seated.

I'd also talk to the vet about prescription meds for daily use rather than only situational, as it sounds like she is starting to struggling on a daily basis which will seriously impede learning (but I'd also try something different for one-off stuff).  And while you're there, I'd talk to them about starting joint support and possible sources of pain (e.g. perhaps some arthritis starting that hasn't shown externally yet), as noise phobias and pain very, very often present together.

Thanks for your reply.
Its funny that you should mention pain as she has slowed down a bit, but I assumed it was the anxiety.  I don't think she is in any pain but she might be getting a bit stiff, so I've ordered her some YuMove chews. And maybe it's time I invested in a little set of steps as she sleeps on my bed, and it's quite high. It can't be doing her back much good jumping up and down that high.

I would get her checked out.  Slowing down to me says pain, especially in a toy breed that's only 7, and with chronic anxiety issues - that means chronic bodily tension, which creates pain.  Stiffness is also typically a sign of pain and again, she is not an old dog.  Steps are a good idea.