(Apologies if this is not the best part of hpc to put this)
http://www.electronic-payments.co.uk/
The Electronic Payments Tool is impartial and you can 'Use the Tool' to compare the cost of UK online payment solutions according to your own business requirements. This will save you hours of research
Use the tool (requires registration) https://paymentstool.electronic-payments.co.uk/ToolInput
QUOTE
The Electronic Payments Tool was intially funded by Scottish Enterprise and the Business Link to provide merchants with a clear understanding of what you need to do to take secure online payments from your customers. The site is managed by RSTO who provide the government accredited www.TradeOnlineProject.com ecommerce implementation service.