Can i say...

"Work" is uncountable here, so you should use a singular verb, "a lot of work was / has been postponed."

"Jobs" and "tasks" are countable, so you'd say "a lot of jobs / tasks were postponed."

Hi,
There is a lot of work to be done next week. Perhaps the original plan was that the work will be done next week. There is no suggestion here that the work has been delayed/postponed

A lot of work was postponed to next week. Perhaps the original plan was to do it tomorrow, but now the work has been delayed until next week.

Best wishes, Clive