[txsl]

If you are willing to switch banks, I'm aware of Natwest's Bankline, which takes in a CSV like file and you then authorise the whole tranche.

Does Barclays accept payment requests on paper? You could generate files which you can hand to them and ask to process.

Also come across something called Envoy Transfers before, which is somehow related to Worldpay. When I was being paid via a freelancing platform, I put my bank details into their (Envoy Transfer's) site.