Extension/knock through - where to start

[DIddled]

Looking for advice- we live in a 1930's 3 bed semi which Has a side single storey extension and a loft conversion which isn't brilliantly done- both were completed well before we moved in.

We are looking to remodel our house , the ideal would be knock through kitchen diner and some sort of extension to give more space , a utility and extra shower.

We will be adding to the mortgage to fund this , no equity issues mortgage is about 120 k on a house value of around 250k.

Where do we start- do we speak to builders? Do we need an architect- it's not a mansion so can plans be drawn by anyone other than an architect?

Roof also needs replacing - it's ancient and has served us well thanks to a fantastic roofer who have lovingly patched it up.

Worth mentioning that our back garden is pretty small, but we don't use it much ( two adults and a 14 y o son) .

Any pointers on where to start would be appreciated :) Happy Boxing Day.

We've almost completed a kitchen extension. It was 2m deep by 8m long so didn't need planning permission.

We started with an idea of the size and went to a kitchen designer to make sure the space we thought we wanted actually worked in design terms.

Since it was a simple single storey pitch roof square box we went to a building consultant to knock us up some rough plans which we submitted to the planners to confirm we didn't need planning. He then revised these and annotated them to be a building regs submission. He also helped us write a tender for builders. He charged about £1400 in total.

We put the tender out to half a dozen builders and got 2 replies, then found another builder through staff at dd's nursery who we liked.

We also employed a structural engineer since we were knocking out the back of the house. He did all the calcs, noticed that the rsj put in form previous works was sagging a little so factored that into his calcs (turns out the back of the house was supported on a concrete lintel not an rsj). We now have a structurally sound house. He charged £400 which included a site visit.

We have the best builders in the world who managed to leave us with a stove and a washing machine for all but a week of the 2 month build (and that was when they had to take the floor up). I think the builders' costs are iro £30k plus electrics (complicated lighting system through 4 interlinked spaces and discovering the whole house was on a single circuit - the sparkys found the wires by feeling the warm spots on the walls) and plastering (we decided we wanted wet plaster; plasterers stropped throughout). Plumbing was complicated by switching from oil and lpg to gas and trying to integrate into an archaic heating system embedded into the concrete floor...

Our new kitchen came from a local independent kitchen supplier.

It's been absolutely worth it; it's not quite finished; lower units are in and the guys are back in the new year for top cupboards, work tops, tiling, bathroom fitting and a few other bits and pieces but we've had the space over christmas and we're utterly loving it. Camping in the front room with 2 pre-school kids, eating out of the microwave, with intermittent power and water has been challenging at times but we were prepared for that and it wasn't as bad as we feared.

Thank you golemmings, I needed to read that.
We are very excited about the space (and the kitchen!) but I'm a bit nervous about the actual building work, although the builder is planning to do as much outside building as possible before knocking out inside walls which doesn't sound too painful which