E s a tribunal

Hi can anyone help me. i was getting full rate esa last year after my first medical.I went for my second medical in april this year, my health hadnt changed, i have osteoarthritise in both knees,and i am on heart tablets. they refused my claim i appelled and i have got my tribunal on monday 24th june. has anyone been to a trybunal and can explain what its like.
any help would be appresiated thanks.