You can claim ESA -either in the support group( means you are totally unable to work or that if you do ,it will make condition worse) or the work related activity group which you will only get for a year and you have to attend job interviews every fortnight or show that you are retraining /applying for work.
You can also try for Personal Independence Payment ( PIP) but you have very little chance of getting unless you are completely bedbound and reliant on carers.
There are some excellent websites and sources of help out there
Endo UK used to do a factsheet on claiming benefits - check to see if you can download updated one.
Benefitsandwork.org.uk is a charity which provides ,probably the best info and help available to complete ESA and PIP forms.. It does have a small joining fee, though lots of good info is available free, but this is well worth paying( about £18 -you can get half price fees sometimes).It has helped me successfully claim DLA AND ESA, for years.
Citizens advice, as already mentioned - they will fill a form for you, but through my own experience I do not recommend this for endo, as it is not sufficiently well known .
I would think you could claim ESA. With all benefits it is about knowing how to fill the form well, so they don't ask you to a medical. Forms are examined initially by a non medical person, but it its a case of knowing how to answer. To be deemed fit to work - you have to be able to do tasks repeatedly, reliably and without serious danger to your health. If you have to stand and are unable to do your job seated,then that is sufficient.But if you are at a desk job,they will argue that you can do it,if you dont stress how bad the endo symptoms are.So with the pain, fatigue, often heavy bleeding or endo and the fact that we are either in agony or doped to eyeballs on painkillers - can you do your job well? Can you do it all day,every day, without being off every month?I was a teacher and there was no way I could do my job as I could barely stand up straight and was in so much pain I was collapsing and being carted off in ambulances! However I also have other serious health issues, so added to the endo I have managed to qualify for ESA.
Turn2us is a great website, detailing all available benefits and you can do a benefit check there as well.
Moneysavingexpert.com - fab site and has details of benefits also.
PM me if you want to discuss more personally-click on user name and I will give my private email.
There is help out there, if you need it. We moan about welfare state,but I for one am thankfull it has been here for me.There is a huge hate campaign going on from Govt and media,trying to suggest that we are all benefit frauds and this is making it more difficult for genuine claimants,whose lives have been destroyed and turned upside down by endo and other illnesses.
Sending you a big hug.