I'm clueless- where to start with house extension?

[peoplepleaser1]

We live in a fairly classic 1930s detached 4 bed. It was originally a 3 bed and has had a garage with bedroom over added to the side in the 80s, plus a sort of conservatory (mostly brick, one half height glass wall with Perspex roof).

We want to make some improvements / and possibly extend a little but really don't know where to start. I think maybe we need an architect first- does that sound sensible?

In terms of work done we are considering:

We have to replace the 'conservatory' roof because it leaking, and not with Perspex as it's a so inefficient but we think this will mean the roof needs some strengthening work to allow it to take something heavier.

We'd like to add a downstairs loo mainly for our ageing parents.

We would like to extend the kitchen slightly, and knock through to what is currently the conservatory to make one larger room.

Can anyone give me some tips about where to start please?!

We made a very clear list of what we wanted to achieve plus a couple of sketches and photos from the internet of the sorts of things we liked. Based on that a builder came to give a rough quote. As that was within budget we then hired an architect who discussed the practicalities and made suggestions. I invested in a copy of the Haynes Home Extension Manual and found that very useful as we hadn't done major building work before.

We called out a builder first to see if what we were wanting was doable. They agreed it was and gave us a rough idea of how much that would cost. He did also come up with a few other great ideas (bigger!) and also recommended an architect. We went with our original plan as was all we really needed and the architect drew up the plans and submitted for planning permission. Based on the plans we got several quotes before instructing a builder to do the work.