Hello,
With regards to your first question (how to file in the US); it depends if you have children. Assuming you don't, then you have the choice of filing as Married Filing Separately, or Married Filing Jointly. (You cannot file a Single). Which one is better for you depends on your circumstances, as if you choose to file as MFJ then you'll need to report (and pay tax on) all your husband's income too. The advantage is that you get a double Foreign Earned Income exclusion, if your income is too low to qualify for Additional Child Tax Credits then you can use your husband's income to possibly qualify etc. It all depends on the circumstances. If you have children, then you can either file as Head of Household, or MFJ. If you do want to file as MFJ then he'll need to obtain an ITIN on a W-7.
The UK works differently. There is no option of choosing a status; for Income Tax, (if you need to file) you must file separately, and for Tax Credits (if eligible) then you must file jointly. Tax Credits are the UK equivalent of Making Work Pay/EICs/Additional Child Tax Credits etc, but are not filed together with a tax return, and can be dealt with by telephone mainly.
Also, unlike the US, most people in the UK do not need to file tax returns. Generally you only need to file if you are self-employed, have property income, large amounts of savings income, you earn over £100,000 pa, or if you have tax to pay that wasn't deducted at source, or need to claim a refund above a certain amount.
If you do become an independent contractor then depending on how you trade (i.e. self-employed, through a limited company, or through an umbrella company), you may need to file a tax return. You mention that you may be "hired" as an independent contractor; the UK is quite strict as to "deemed employment" (Where people are employed, but claim to be self employed in order to save on National Insurance contributions etc), so you need to check you are IR-35 compliant.
What to read to get starting on UK taxes:
www.hmrc.gov.uk is quite useful.
Just to point out that if you are UK resident, you'll be taxed by the UK on worldwide income (unless you choose the remittance basis of taxation), and as a US Citizen you'll be taxed also on worldwide income. Foreign Tax Credits, the Totalization agreement, and the DTA mean that you only rarely have to pay tax twice on the same money.
If you are not earning this year then you won't need to file a US tax return either.
Common traps for US citizens in the UK:
1) UK ISAs/Pensions - tax free in the UK but taxable in the US, also beware PFIC (passive foreign investment companies) issues.
2) Trading through a limited company - whilst this is very tax efficient in the UK, if not done properly, can be disastrous from a US perspective.
3) UK bank accounts - not a problem per se, but if you have over $10,000 in foreign bank accounts, this needs to be reported (not on tax return)
This list is not exhaustive, but from experience these are common issues that get people tangled up, and where they to be sorted out beforehand, could have been straightforward.
All the best
Andrew