derwent macdee cystern repair?

i am trying to change a diaphram on my toilet as not flushing your tips are good but my problem is the nuts holding the syphone underneath are encased by the toilet bowl ( there is a flange on the bowl that goes across the tank and covers the nuts i need to reach it looks like the whole bowl may have to be removed) any tips as i cant see any way of getting to them without moving the toilet bowl which will have to be done by a plumber HELP