Sorry you are going through all of this OP. Have you heard of a website called Hub of Hope? You put your postcode in, select the help you need (I recommend selecting crisis as at least one of your options) and it will bring up a list of support options in your local area.
www.hubofhope.co.uk
Does your workplace have an employee assistance program? They usually have support for situations like this. What industry do you work in? If anything to do with Grocery (eg work in a supermarket or for a food manufacturer), you can contact GroceryAid for support.
Is there anyone at work you can talk to about what is going on to see if they can give you a few days as paid time off to try to sort things out?
The main thing is that you take some time for yourself to look at your options. Things may feel hopeless right now, but they won't stay that way forever.
Good luck in getting a GP appointment. If you can't, call 111 and tell them you are feeling suicidal. You can also go to A&E for this - it IS an emergency.
Do you have any churches nearby? Many will offer support even if you aren't religious.
Are there any community groups you could join? Do you have any hobbies?
Do you have anyone you can either stay with, or can stay with you for at least a couple of days? Not sleeping well always makes things feel worse, so if you can get a couple of nights sleep, hopefully you'll feel better prepared to make a plan of how to feel better - what can help you, what choices do you have with the things you want to change, etc.
Good luck OP. I'm not saying it's easy - but the only way from here is up, so things have to get better!