Contractors aren't entitled to those things in the US so why would they be when working over here? Just curious... I feel like I'm missing something my employer may need to be doing. I'm also working on my self assessment and trying to figure out if I can file consistent tax years (because you can't claim no deductions in the US until you've had a year with no tax liability).
Actually this response is not meant for Margo so much as the OP. I think Margo's situation is different in some ways and similar in others.
I'm no tax expert, but I do know that it is very important from a tax perspective for you to know whether you are a contractor or something more similar to an employee. Just because the company says you are a contractor is NOT enough. The way the contract is written means a lot, but that is superseded by the actual working practices. You must prove that you have direction and control over the work and how it gets done. And a ton more stuff. It's a fantastically complicated concept and is open to plenty of interpretation. Google IR35 for the opening of the rabbit hole. The reason this is important is that you must structure your personal business practices according to whether you are considered an almost empoyee or an actual independent contractor. If you get it wrong, HMRC can audit you at any time and collect back taxes that you should have paid. This can be a really, really expensive and bad thing.
There is a well known company called QDOS
https://www.qdoscontractor.com/ir35-contract-assessment
that offers to help you figure out whether you are inside or outside of IR35 by reviewing your contract and your working practices. If both of these pass, then they will cover you with insurance against any prosecutions by HMRC.
If they determine that you are inside of IR35 and thus sort of an employee, then they can probably suggest an accounting device called an umbrella company that can help you collect your money while doing what you need to do to satisfy HMRC. Keep in mind that all of this stuff and all of this advice is appropriate for UK citizens to stay straight with UK taxes. It is probably completely inappropriate for Americans in terms of what is best for US taxes. You'll have to pay for a lot of advice from someone who knows the US system to be sure, unless somebody like Guya will offer advice here.
It's pretty expensive to hire all the accountants on both sides of the ocean to manage your contracts and taxes, that's why independent contractors get paid a ton more money than salaried employers (like 4 times more). They also have to pay their own taxes ( I regularly write checks to HMRC for £18,000) and save up for holidays, pensions, sick days and insurance themselves. If you are not earning enough money to pay these accountants , advisors and insurance for yourself, then alarm bells should be ringing.
By the way, here's the link to my accountant, who has a ton of resources about contracting on his site. I think they've even got sample invoices and templates. I am not endorsing them as accountants, that's a whole other post but you might find some handy stuff there.
https://www.sjdaccountancy.com/
I hope this helps you.