I am looking into the idea of doing a self-build and trying to get an idea of the costs involved before actually committing to it (e.g. by buying land or paying architect fees). I would like to know if the whole thing is at all feasible before investing a bunch of money in it. I have seen all the usual £/m² estimates, but these seem to vary quite a bit and don't always include all of the associated costs (e.g. architect/SE fees, applications, warranties/insurances etc.), so I'm wondering if there's a way to get a more accurate idea of costs at this stage of the journey, or is this just what people go on to start with and only get more accurate estimates as the build progresses, e.g. after land is purchased and designs are drawn up by an architect etc.? I have seen cost estimating services such as estimators.com mentioned in this forum, but it seems that these require designs which I presume would only be done much further into the project and after already having invested quite a lot of money.
Any tips for how I should go about initial budgeting/estimating would be greatly appreciated 🙏