OP, your debts aren't really that big now that you have a regular job. (I once had credit card debts equivalent to a year's gross salary). Once you have cleared the mortgage arrears, council tax and electricity debt, things should be a lot more manageable.
It is really hard to start getting a handle on things when it seems like one huge mess. It might help if you just started on one bit of the problem, so that you're only dealing with a small thing at a time.
If getting to the bottom of what you owe is scarey (which I'm sure it is), just work out your current outgoings, then see where you can claw back a bit of spending.
If you're spending £300 a month on petrol, I reckon you're using around 250 litres of fuel a month. Saving just 5p a litre by filling up at the cheapest place possible would save £12.50 a month. When I practised fuel efficient driving, I reduced my petrol consumption by 10%, so if the same works for you, that's quite a significant saving.
Even if you buy a meal deal sandwich lunch, that's £3 pd, £60+ a month. You could reduce that by 50% if you took a packed lunch to work.
Try having a month where you don't buy anything that isn't essential and that doesn't have to be bought right away. We do this every now and then, and we can reduce our shopping bills from around £300 a month to £200. Buying cheaper alternatives like own brands can really help here.
That will help you feel a bit more in control of things, when you find that you can cut back, and then you might feel able to address the question of overall indebtedness.
When you do that, remember that that global total may seem huge, but for a lot of those things all you have to cover for now is the minimum payments for most things.
Speak to your mortgage company and see how little they will accept towards your arrears. Do the same with your electricity supplier - if you've been paying £200 a month for a while, your debt should have gone down a fair bit. Also check your last statement and make sure that they got a meter reading. If you've had estimated bills for a while, check if they've been overestimated (ime they usually are) and give them a reading so they can recalculate the bill.
Your council tax debt should be nearly paid off after a couple more months, then it should go down a bit. Make sure you're getting the 25% single occupier discount.
Taking these small steps will help you feel more in control, which will ease your anxiety. Then you can start looking at getting a DMP in place for dealing with the rest.
Oh, and check you're not paying fees for your current account: one of my clients had been paying £10 a month for theirs, because it included travel insurance. She never travelled abroad, so it was just a waste of £120 a year, and she'd had it for 5 years!