Any advice for sending money successfully from a Barclays UK account to fund a Coinbase account? Is this doable nowadays, or will my Barclays account get flagged or frozen?
it is doable. but expect hassle
you will get the transfer paused where the bank will contact its listed number for you and put you through to the "crime prevention/fraud prevention line"
they will ask you to confirm your identity and ask you some questions such as
"are you being held under duress and being requested to make a payment by someone"
"have you been contacted by some (scammer) saying you need to pay them in crypto!
"do you understand the risks of investing"
"do you give full consent that you are making this payment of your own free will and understanding of the risks"
or something along those lines.
if your using a business bank account that usually moves large amounts like you suggest the hassle will be the same as your other payments. but if this is the first "large" amount from this account. expect them to want to double check