Great idea, except for any business to succeed there needs to be cash flow. As long as I am unable to transfer BTC back to GBP the business wont last long
Then either start as a hobby business, and simply sell what you can sell; or just add bitcoin payments to another existing business model. Maybe bitcoins will become a significant part of the business, maybe they won't. Doesn't really matter, if the goal is to aquire bitcoins for your own purposes cost effectively.