From the information you have given, it should not be difficult to file the US return yourself. There are several choices as to how you do this.
First, a UK P60 will not be of help. The UK tax year is 6 Apr. to 5 Apr. of the following year. A P60 will only give you the total taxable income during that period. The first 4 months required for the US return will not be included on the P60, but you would have an additional 4 months from 2019 which are not in the US 2018 tax year. The US tax year is 1 Jan. to 31 Dec. of the same year (2018 in this case). For the US return, you'll need to review your records to determine the exact
gross amounts you received for each month of 2018. You would need to do this regardless of whether you prepare the return yourself or use professional assistance.
As for choices, you may use commercial tax preparation software such as TurboTax or TaxAct. You may also qualify to use one of the IRS FreeFile options.
https://www.irs.gov/filing/free-file-do-your-federal-taxes-for-freeYou may have professional assistance, and any cost below $200 is
cheap! The majority using a pro pay over $500 for professional assistance. Lastly, you could download the appropriate forms from the IRS site, and complete them yourself, and mail them to the IRS.
For help as to how to prepare your tax return if doing it yourself, the first port of call is IRS Publication 54. 54 gives information for filing from abroad.
https://www.irs.gov/pub/irs-pdf/p54.pdfAdditionally, the ACA have prepared a primer of what is involved and explains the different ways of reporting for a US tax return.
https://www.americansabroad.org/us-taxes-abroad-for-dummies-update/You do have an automatic extension to file which is 15 June. If additional time is required, you may file for an extension to 15 October, but you must file for the extension before 15 June.
Since you have been in the UK for 1.5 years, you should qualify for, and at least meet, the requirements for physical presence on form 2555. The fact you have had 3 different employers will make no difference.
As for FBAR (FinCEN 114), yes, from the figures above you would have to file an FBAR since the aggregate is over $10,000 (and don't forget Part III of Schedule B). Although the joint account is in two names, you have the ability to determine dispersal of all the funds in that account. FinCEN 114 is an informational report only, and is sent to the Treasury. It has nothing to do with your tax return, or tax due.
For a USC with an NRA spouse, filing 'married separate' is
generally preferable, but in a few cases, MFJ gives better results (for example, both are USCs). Given the above figures and the fact you indicate a preference for 2555 (FEIE), filing MFS would seem the route to go.