Knocking through and redesign kitchen. Where to start?

[flingoo]

Hello everyone. This probably sounds like an incredibly dumb question and I apologise in advance.

In the next few years we would like to knock through our kitchen wall to an adjoining room to have a large kitchen diner. Where do we begin in this process? Is it structural engineer first? Or do we hire someone to project manage it all and real with all that?
Or do we map out roughly what the space will be and work out the design ourselves?

The knock through will involve blocking up doors, potentially moving windows and there is likely to be some structural support needed. But I feel like I want to look at plans and ideas of how it could all be.

I've never had non-essential building work done to the house so please excuse my ignorance. Could anyone give some advice of the steps?

I would find a builder who can take on the work while also pulling on contacts such as in building control.

My Dad is a builder. Whilst he does most of the work, he gets other people in to do the calculations for steels, obviously sign off etc.