The old style Employment and Support allowance (ESA) no longer exists and you have to apply for their new version.
I think to apply you have to go onto the Gov.uk website and look at the criteria.
You may be able to apply for Personal Independence Payment (PIP) too.
Be aware both benefits carry a different set of criteria to claim it so it is best look at the website information to see if you think you fill their specifications. With PIP for example you can get the benefit whilst working if you have a debilitating condition. ESA is more as to why you cant work.
Therer are various forums on facebook that can help you look at the criteria. If you need further information then please message me and I will give you the group names.
Universal Credit was introduced to 'blanket' a whole host of benefits and you may find your area has rolled it out. Again there is a facebook group that can help you find out if your area is a 'live service' are or a 'full service' area.
The groups that I can put you in touch with I have used myself for advice when I left my job due to ill health and I'm not pension age.
I see the CAB has been advised, they should be able to help you but they are an over subscribed company and you may have to wait a while before anyone can see you, dependent obviously on your area.
Good luck to you