Combi or conventional system if I want the ultimate shower experience??

[Hot&Cold]

We would be putting in a large main bathroom with big freestanding bath and rainfall shower along with a good sized ensuite with rainfall shower.

Can you work out your predicted water flow peak demand in litres per minute with your water hungry showers and other mains water outlets,then get water heating equipment that will satisfy your demand of pressure,flow and temperature.

Edit,get the external water flow/pressure checked by the water company or a proper plumber. It could be pish