Don't know about the ins and outs of the financials, but ...
Don't forget the potential planning consent issues of buying a domestic house and running it predominantly as business premises. In addition some (mainly more modern estate) dwellings have land title constraints to prevent their use as business premises.
Finally don't overlook the potential loss (long-term) in terms of capital gains, because you can't claim 100% of your business as your 'primary residence', which is of course except from CGT.