Tankless Coil for Oil Boiler or any other suggestions please...

I am days away from changing my oil boiler for a new oil boiler. I currently have a electric hot water tank for hot water. The plumber told me he could add a tankless coil in front of my boiler. I heard that you run out of hot water quickly with this as I have three girls. And the boiler would be running year round. Any suggestions? Should I use a electric hot water tank or perhaps a separate oil fired hot water tank? Could you guys please help me out? Thanks so much....