Potential extension. What do we do?

[bookworm8500]

Hi all,
We are considering an extension. We'd want to build an extra bedroom upstairs over a car port.

There are a huge number of drains on our drive as it used to be the waterboard's land and I believe we'd need to leave them accessible.

My question is, what do we do? Do we go to a builder or an architect or what?
No idea the order of these things as never done this before

Thanks in advance

We have done an upstairs extension over a garage. We had the architect first. They arranged a structure engineer and gave us drawings that include both planning permission and building regulations. Then we got builders to quote on those drawings. The council planning department came out and check the progress against the plans a few times, and I got the sign off pretty soon after it's completed. The builders won't do it unless we have building regulation drawings. They say it's different if it's a bog standard one story kitchen extension. Those, they can apparently do their own drawings.