[UK Providers] What are the minimum and maximum payment amounts possible?

In the UK, the minimum amount for a payment is £0.01.

Maximum payment amount limits are set by the payer's bank, and may be dependent upon the specific bank account type and conditions such as the current balance or how many payments have been made recently.

In the UK, Faster Payments maintains a list of general limits here

Here's a list of general daily limits per provider, please refer to each bank's website for more specific information:

Provider	Payment Daily Limit	Observations
Lloyds Banking Group (Lloyds, Halifax and Bank of Scotland)	up to £5,000	Limits may differ for Websaver or Express Cash accounts.  It also considers the payment context code, which is related to the origin of the business.
NatWest Group (RBS, NatWest and Ulster)	up to £20,000	Limits vary depending on the payment journey, type of account, and the use of a Card Reader for consent. Retail customers of NatWest, Royal Bank of Scotland, Ulster Bank (Northern Ireland) and NatWest International have a default limit of £5k per day. However, customers can amend that daily limit through their online banking portal. Please refer to this article for a breakdown of the limits across brands and account type.
NatWest commercial & corporate customers	up to £1m	Only for Bankline customers. £1 million will not be the default Faster Payment limit for Bankline customers. Instead, it will be the maximum limit that customers can set.
Barclays	Personal: £10,000 Premier: £30,000 Business: £50,000	Payments to a new payee have a £2000 limit for Personal accounts, and £5000 to Premier accounts.
HSBC	£25,000
Santander	£25,000
Nationwide	£10,000
Danske	£25,000
AIB UK	up to £20,000	Limits may differ depending on the authentication method (PAC or Card Reader).
Revolut	up to £500,000	Specific limits: £250k per transaction, £500k per day, and £1m per week. One user cannot make more than 50 transfers in 24 hours, or more than 200 transfers in 7 days.
Monzo	£10,000	For this limit to be increased, the user should contact Monzo's Support team.
TSB	£25,000
First Direct	£49,999
Starling	£25,000