hosting can never be as good as owning your own, the hosting people need eat also. business electric is 11p a unit, better yet is a diesel generator it will get it down to a penny a unit or less.
If you do the sums its a no brainer to send miners abroad (when subject to vat).
Business electric is around 11p + VAT + CCL those add quite a bit. Hosters usually have MUCH cheaper electric that offsets the hosting cost.
Let's use an S3 as an example over 6 months
UK
Miner £180.00
Import Duty £36.00
Electric (182 days at £1.30) = £236.60
Total £452.60
USA
Miner $295.00
Import Duty $0.00
Hosting (6 months at $75) = $450
Total $745.00 = £450.00
So there is not a lot in it, but if you run a few machines you have to start thinking about cooling, and office space, and rent and rates etc etc none of which are a factor when hosting.
The diesel generator sounds like fun though