Planning permission is unlikely to be an issue unless it is in a conservation area or the pavements are narrow. What are the residents like? Do they have money to spend and would they go for FTTC if available - you probably don't know, however getting them to complain to BT will carry more weight than a business.
Yes you might require additional hardware to manage two lines, but it is likely to e cheaper than having a leased line.
M H C
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