I can't find anything for a shawarma, but I had a look on essentialsweightloss.co.uk and they've got a few listings for kebabs - not sure if any hit the mark, but might be in the same ballpark!
Doner kebab in pitta bread with salad, small portion (230g) : 586 kcals, 37.3g fat
Shish kebab in pitta bread with salad, average portion: 356 kcals, 9.4g fat