Is it possible to invest in USD as a UK resident?

A company should do the job because it'll be US resident but I can't help with the cost and work it'd take.

A person who is not a US citizen or green card holder would need to get an Individual taxpayer Identification Number (ITIN) to invest in the US or alternatively it might be possible to use a W-8BEN form to reduce that tax liability. This is more work for the US P2P business.

US citizens or green card holders who haven't renounced citizenship are taxable on worldwide income and there are extremely adverse tax costs for US persons who use most forms of UK or EU collective investments. P2P is probably less painful but I haven't looked at the details. It can be so painful that using US investments can beat using UK or EU investments just on tax grounds. If this paragraph might apply to you you're going to need more US tax advice than can be given here, it takes a pro who knows your full situation and both US and UK tax law to do it properly. Those firms do exist, specifically to help US people who live in the UK or elsewhere.

Hi, I don't really understand what you are trying to do. Are you trying to avoid paying the FX costs of moving the money to GBP or EUR? Or do you need to keep the money offshore? There are funds you can buy which are heavily invested in US P2P loans and many brokers allow investments in US equities, but you might have to bring the money into the UK first, and pay charges. If the amount is large enough it might be worth speaking to a private bank, or at least one of the more internationally minded banks such as Citibank or HSBC.

HSBC opened a usd account for me about 2 years ago while I was in the office.   I had to go in to do identity bollocks (despite being a customer for decades), but apart from that it was ok.  Several brokers (TD for one) have currency accounts which might work.   
I too have failed to get onto any US platform, yes the collectives might be a way.  Thanks for the suggestion - any in particular?

That incident wasn't FATCA but apparently suspected fraud, though given the nature of the payment I don't see how any reasonable person could think it was fraud.

Initially. then we are talking about how the Financial Ombudsman Service rules and whether they can direct Barclays to change the information or to pay redress.

They don't have FATCA button to press. The banks are VERY scared and this guy was a danger. Hence, they pressed the danger button. The linked article has nothing to do with NYC or AML, it's about a bank that has a customer that could potentially shut down their company if not handled as per US regulations. If in doubt, throw them out.

An identified customer banking a valid check is not fraud, it's that simple. As the article correctly states, banks are free to share their concerns about a risky customer and do, but there is no FATCA button to press. And any customer banking US checks could indeed be very dangerous for them, but not due to fraud. A UK citizen banking a US cheque is not committing fraud, but he IS ringing alarm bells with the FATCA compliance team who are in the business of making sure the bank is not shut down by the USA for incorrectly reporting the presence of "US persons" on their books. I'm not sure how anybody can come to the conclusion that this is about fraud when there was no evidence of fraud. Mind you, many are completely unaware of the monster that is FATCA and don't understand why the banks are treating Americans like a dose of clap. Regardless, I will be giving the USA a wide berth, if nothing else because any US "indicia", such as a check for $11,000 and I will be kicked out of my Belgian Deutschebank account.