If you are looking for high risk merchant service providers in UK, then this surely means you got declined by most of the banks or your previous payment processor terminated your account for further processing. In order to process payments for your website seamlessly, you will be required to have a high risk merchant account.
To get a high risk merchant service providers in UK, first it is vital that your business must be registered in a EU country and you must have a physical presence as well. Further you will be required to furnish KYC documents like business registration documents, latest utility bill, National photo ID, personal and business bank account statement and your previous processing statement (if you processed payments before on your website).
If your website passes through compliance and submit all proper KYC documents as asked by your high risk processor, then this increase chances of getting final approvals.
For more information on high-risk payment gateways in UK, visit: https://quadrapay.com/high-risk-merchant-service-providers-uk