Heating...Kitchen...Bathroom...where to begin?

[clueless_twinterychildh]

Just after alot of advice please as I just don't know where to begin. And as you will gather from this message my technical terms are non-existent and don't really know what's what so please bear with me...

HEATING
Is the preferred heating system a combi boiler?
I have a very old one and it's not a combi-boiler so I am thinking I want to update the heating system in the house. Sometimes, when the heating you can hear the pipes rattling....
How big a job is this? Will all the pipes need replacing and moved etc...
Should I do this before fitting in new kitchen and bathroom?

KITCHEN
The whole kitchen needs replacing.It is a large one big enough to be a kitchen diner. Tiling, plastering and flooring needs to be done also. Which do I do first? Is it better to have the kitchen installed by the supplier or get a separte fitter?

BATHROOM
Same as above really.

Thanks for your time and looking forward to lots of enlightenment :)