According to the report obtained the Guardian (which Downing Street denied, while Blair has called such plans "premature"), the most invasive military action contemplated is:
British troops to protect refugee camps being harassed by marauding militias. This creation of safe zones would be the most risky of the options and would require the agreement of the Khartoum government, which would be reluctant to give it.
In response, Sudanese Foreign Minister, Mustafa Osman Ismail suggested that if Britain sent troops, the Sudanese would pull its army out of Darfur, leaving the British to cope with an occupation situation worse than Iraq (
Blair: Nothing is Ruled Out in Sudan).
As I read it, Ismail's comments are meant to up the stakes as a signal to back off, and may be taken as a lack of agreement. Notably, Ismail does not state that the establishment of safe zones would be opposed militarily by the Sudanese government. So I would say that even though relations are tense and one sees intransigence on all sides, there is yet room for negotiations.