After much talk of moving we are finally realising that we might be better off reworking our own house. This is the floor plan from 8 years ago when we brought it and very little has changed bar the addition of an en-suite in the master bedroom (crudely drawn by me 
)& some minor cosmetic work.
We will ultimately be selling as our plan to move area in a few years still stands so whilst we will be doing it initially for our own benefit, it does need to work financially & advice is open up downstairs & find a way of adding a 4th bedroom upstairs.
The obvious is big open kitchen/diner at the back with bi-folds onto the garden, living room at the front but can't work out where to house wc or what to do with current kitchen (playroom &/or utility would be ideal). Upstairs we reckon bathroom + bit of landing could be bedroom 4 and maybe big cupboards a family bathroom but it all seems a bit tight.
We can move out for 3 or 4 months (6 at most!) and would get an architect & project manager as we both work but nervous about spending money if we can't make the space work. Would a major remodel take longer than this and are we talking £50/60k as DH thinks or £100k as I think (any more and it's not viable!)
Any suggestions? Is this complete madness?