Buying house for extension & HMO conversion (needs PP) - how soon to involve architect?
Just had offer accepted on a house in Solihull that we want to put a 2-storey rear extension on and turn into a 6-bed professional HMO. Local council's HMO officer is in favour (it's a rare borough that actually wants to ENCOURAGE HMOs) and a brief chat with a planning officer indicates that our proposal should be feasible from a PP point of view, albeit possibly with a tweak or two. There are, of course, a few issues that could prove problematic (e.g. all interior walls are brick and we want to move one that supports the roof) but surveyor said that the house is "built like the brick proverbial" and he seemed happy enough with the proposition. Target date for completion is 4th April.
How soon should I involve an architect / structural engineer? Don't want to jump the gun as we got gazumped four times last year and the last time cost us over £900 - but equally, once we've completed we want to apply for planning permission and get started as soon as possible.
I've got the name of an architect recommended by the surveyor but does anyone else have a local architect / structural engineer they'd recommend for this kind of job? Builder/trades recommendations also appreciated.