Re: Unaffordable leased lines
With a leased line, you're paying for the service level rather than the "speed". DSL based services often suffer performance issues and can go down for days without any comeback on the supplier. Most leased lines have a 99.99% uptime guarantee and if they do go down, the supplier has to start paying compensation so they tend to get fixed quickly. Leased lines use the national Ethernet network too which has much more resilient kit and much lower latency than the broadband network. That said, £550 for 20Mb, presumably on a 100Mb bearer does sound a bit steep. We normally charge around £300 - £400 for 30Mb on 100Mb bearer, but it really does depend on which services are available in your area.
Did you try EFM or Ethernet over FTTC? Both often work out cheaper, faster to install and still qualify for the Connection Voucher scheme.