Usually aim for a split bill adjusted for those drinking booze or having desserts etc. Splitting a bill based on who had what is usually a nightmare and means people conveniently forgot about service charges.
Last night we went to Dishoom and the bill was £104 between six, but only me and my partner had a (shared) dessert and had a drink each, the others had tap water, so they paid £16 each and we paid £20 each and everyone seemed happy.