We are currently doing our loft and will then go straight into doing the kitchen extension / downstairs refurb - knocking down walls, making it open plan. We knew exactly how we wanted the downstairs to be - layout, etc, so didn't need an architect, so went straight for a structural engineer, because after the design plan, what you really need are the structural calculations to submit to planning. He advised on the structural side e.g. whether to take out the chimney breast or not, drew up the plans, submitted the plans to planning and did all the liasing with the council, we had to make some simple revisions to the plans. Then we were able to hunt for a building co. and give them the plans to quote on. All v simple and I wanted to be more hands on with the project management in that, possibly saving £. I think it was about £1,200 the plans and submission to the council, etc, which seems quite good. As opposed to some of the all in one cos. who wanted £3,000+ for doing all of that. And finding builders was just hunting for recommendations, phoning, arranging for them to come and quote, choosing who we liked best. Fairly straight forward. So if you are fairly clear about what you want, you could go down this route - structural engineer, don't need architect, then choose building co.
Our structural engineer is:
David Lewis
http://lewisconsultingdesign.vpweb.co.uk/
We are Lambeth, which he knows, not sure about Wandsworth, but we think he did a great job.
We're going with Classic Lofts for the Loft and
http://www.handzontools.com for the kitchen extension, via recommendations and really liking and trusting Robin to do a good job. We could have used Handzontools for the whole thing, but had way before decided to go with Classic Lofts as they did my brother's loft.