Panicking Cat

We are going to be moving house soon. Our youngest cat goes hysterical with fear when she has to go in a cat box (taking her to the Vets makes her vomit and have diarrhoea). Are there any sedatives available in the UK which we could give her before we try to taker her?
TIA.

I have recently bought Feliway spray for vets visits. I spray the inside of the carrier with about 4 squirts 20/30 minutes before travelling. It seems to help. Failing that something like valerian tablets are often used on bonfire night

https://www.amazon.co.uk/s/?ie=UTF8&keywords=valerian+for+cats&index=aps&tag=

I wonder if this is something that might help. Krista seemed almost resigned to it but I left her alone just long enough for her to get a paw out the neck. That was just our first time with it. I think with practice this might be a useful ally for meds. I think it's too easy to get wrong to put it on the vets and vet techs to use it. Maybe you can pick one up and practice with with her with treats, and see if it might settle her.
Cat-in-the-bag E-Z-Zip Cat Carrier, Light Blue, Small - Chewy.com

You might try a few things ahead of time, just to make sure something works - as not all calming products work on every cat. If what V verna davies suggested doesn't do the trick, you could try Bach Rescue Remedy, which are drops you can rub into a cat's ear. A lot of people use them before a vet visit.

Do you have access to Benadryl? 25 mg not 50. You will have to call your vet for the dosage though, it worked very well on OUR move, just be careful not to overmedicate.

Thanks. Will probably have to get something from the Vets when we take the others to be micro-chipped before moving. Never needed to here as there are no other cats within miles and bodies are never found thanks to the local badgers, foxes, crows and other scavengers.
We think she remembers being brought here to be dumped as a baby, in a carrier which is why she is so freaked out by it.

One thing that can help, if not now, later (it takes time) is to leave the carrier out and opened in a room where she is comfortable. Give her treats close to the carrier, slowly getting nearer, eventually putting the treats at the doorway to the carrier, then inside. Try to start training her to see the carrier as something positive. This probably won't help right now, as it take TIME.

That's a good point. I was so focused on the bag disaster from this morning that I forgot about all the good work Krista and I have done with carrier desensitization and positive associations.

This is the carrier I use for Krista.
Petsfit Double Sided Expandable Dog & Cat Carrier, Gray, Large - Chewy.com

I leave it unfolded with the top and front open in her daily environment.

In Krista's case, we have an established fish flake hunt routine. Getting her to go inside was not an issue at all. She follows the flakes. I make sure that I put fish flakes in her carrier several times a day as the fish flake hunt is part of her feeding routine.

Another thing I do with Krista is that I play Music For Cats for her in the living room while I work in the office. Then anytime we leave for the vet, I have an iPod with that Music for Cats loaded. I have that playing in a carrier pocket the entire trip plus lots of fish flake reassurance. (We love fish flakes! She can't get enough, and they don't ruin her appetite. In fact, I often use fish flakes to stimulate her appetite.)

We have also practiced vet visits or parts of the experience so these aren't as stressful to her now. Once I was able to lure Krista into her carrier, we practiced zipping her up, lifting her, and mock car rides with her beside me in the carrier on the couch. Lots of fish flake reassurance throughout.

The overall point of all this is that you can practice stressful situations like the carrier and the car ride while mixing in positive associations and reassurances like the fish flakes and the music to make the situations more familiar and more tolerable. Honestly, if you can get her comfortable with the carrier, that's more than half the battle. Once the carrier is a safe place, everything else is less stressful.

Thanks again, mods and responders.
Bit of a problem in that we have never found any treats that she will eat. Not even fresh salmon. Odd, but none of our three will eat anything but their own food. Strange animals. Tried them with all sorts of things, they sniff them ,turn up their noses and walk away. Perhaps we will have to try fresh mouse guts!
Better half tells me that she has actually seen her go in the carrier before now. It may well be the car journey which is the problem rather than the carrier. Not sure at all. Thanks anyway, we will manage some how, got 5 weeks to come up with something.

You have five weeks to practice car rides then. She may get car sick. You can try the Cat-In-The-Bag or you can ask your vet for something for car sickness.

What about music. If she responds positively to music in the house then it can be played on the car journey.

What Kind of Music Do Cats Like? (Probably Not What You’re Listening To) | Care2 Healthy Living