is it diesel pump?

hi have recently bought a zafira 02 plate 2.0 ltr turbo diesle. it was driving fine then started chugging like fuel wasnt getting through and cut out now it sometimes starts and drives but then it will cut out again. i think it may have something todo with pump and fuel as the gage keeps moving and when it wont start u can hear a buzzing sound i heard that was diesel pump. can any one tell me what they think and roughly how much it will cost.. many thanks kay