Space design - reorganising ground floor - help, please!

[propitia]

We have a through reception space as previous owners removed wall between living & dining rooms. We also have a galley kitchen. We now need to recreate the original separation for our sanity! (music practice, Xbox and homework don't mix well) but we have many options for achieving this eg insulated stud wall or glass pocket doors to separate, create a utility in middle or back of house, open up kitchen to the back reception or not...where do people get an idea of the best options for them with an idea of the cost implications of plan a over plan b? The two architects whom I have met with want around £5k to produce line drawings, not planning or building regs plans and this seems a lot compared with budget, as I will still need to pay for those & have been quoted another £3-4k for them. (In London)
Do structural engineers help with this or do they produce the drawings?
And since I'm asking everything else, can anyone gives me any idea on their costs for drawings etc? It would include the kitchen.

I would start with measuring the outline of the downstairs and drawing that on a plan - do a few copies to draw all over.

Draw in the existing layout. Draw the options for other layouts - you will quickly realise which ones are workable and which aren't. Think about any supporting walls - whether beams would be needed (significantly increases the cost). Think about sound proofing - is it important or not - may help decide if stud wall (with sound proofing) is needed.

Think about lighting, windows etc.

Utility room/kitchen - think about drainage and water supply.

Find out if you need to conform to planning rules, and which building regs are relevant - whether it has to be signed off by the building inspector etc.

When you have done all that and come up with a couple of options, you can get a back of the envelope idea of costs. Then go to an architect or an architectural technician (cheaper) to draw up the plans. Will need a structural engineer too if beams needed. The clearer ideas you have the easier it is for the person to turn it into a technical diagram (and that should reduce the cost).

Thank you Throckenholt - I have indeed started with plan and thought about some of these issues. I am feeling a bit stuck as I cannot evaluate the main 2/3 possibilities in terms of cost. Builders have all asked for drawings before they get into it and haven't offered much idea into which options work better.

Doesn't help that every house in the street has found a different way of organising space to their circumstances. But they are all v small terraced houses so maybe I should look harder at what others have done...