Replacing kitchen worktop and sink/taps

[DaveR]

The job is to remove the existing worktop and sink/taps (leaving units and hopefully the tiled splashback intact) and replace with new ones. There's a gas hob mounted in the worktop that will need to be taken out and put back, but no idea whether it will need to be disconnected/reconnected. Not sure about material for the new worktop yet, but most likely something that will need to be cut offsite. So do I need a plumber (gas safe or not?)/kitchen fitter/carpenter? How long should it take and how much should it cost? Any recommendations for trades gratefully received.