head over to your local citizens advice bureau or law centre, if they're legal aid funded they can help with an appeal and sign you up under a caseworker.
the ESA medical process is a joke now, its basically a list of 'descriptors' which attempt to find out if you can do certain tasks such as 'sitting at a desk' and 'using a keyboard and mouse'...if you cant do the descriptor in question then you score points for that particular test.
except they dont actually test you, they ask you a series of questions, along with the esa50 questionaire you fill in and then extrapolate answers for these descriptors with the multiple answer type questions you answer.
the descriptors can be found on page 69 of the following pdf
http://ssac.independent.gov.uk/pdf/esa-amendment-regulations-2011.pdf
if you score 15 points with descriptors from parts 1 and 2 then you can go into the wrags group, work related activity group basically means they think you can do some type of work.
the descriptors on page 76 are for the support group, if you fit the further criteria for this group you dont have to look for any work whatsoever as you are deemed to ill to work, only something like 4% of all claimants get into this however.
as i say, go to your local citizens advice or law centre, they will be able to assist you with an appeal but the majority of the work any advice agency does is down to the medical evidence they receive back. they can write to your doctors/specialists and use that evidence to argue that the dwp's assessment doesnt cover factors known by your doctors who have been seeing you for x years. letters saying 'mr. x suffers from y illness and takes z medication' arent usually worth the paper they are written on. what we do is create a document listing the descriptors relevant to the appellant and ask the doctor to comment on their understand of their patient's ability to perform these tasks given their illnesses. then ask for a reconsideration with the written evidence so you're not waiting 9 months for a first tier tribunal date.
also if you get any disability living allowance think about requesting a copy of the decision maker's report which might have evidence in you can use for your ESA appeal.
good look with the appeal