The sponsors passport can be just a copy of the photo page correct along with a long form birth certificate?
Ideally you should include a notarised/certified copy of the sponsor's passport page and no birth certificate.
In the past, the UKVI website used to say that instead of a certified copy, a photocopy plus the long-form A4 birth certificate was acceptable... however, this is no longer stated on the new version of the website.
You may be okay with just a photocopy, but to be on the safe side, I would either get it certified or include the birth certificate.
So, you can include:
1) The sponsor's actual passport (not recommended if you might need it)
OR
2) A notarised/certified copy of the passport photo page (I believe the post office will do this for a small fee)
OR
3) A regular photocopy of the passport photo page (plus the long form birth certificate)
Is there a new sample introduction/sponsor letter anywhere?
Not that I know of - the old one used to be on Transpondia's website but the site seems to be no more and I don't know of any other sites with a letter on it.
Essentially, the sponsor letter should include:
- ability to sponsor the visa (being a UK citizen)
- current employment/how the financial requirement is being met
- where you will live in the UK (how the accommodation requirement is being met)
- a brief history of the relationship (when you met, how often you visit each other, how you keep in contact, when you got married, and why you have decided to settle in the UK together)
- a list of the documents that the sponsor is contributing to the application
If the applicant will be including a cover letter it can include:
- type of visa applied for
- intended travel date that the visa should be made valid from
- explanation of anything unusual about the documents in the package (i.e. if something is missing, or if there are large transactions on bank statements)
- explanation of any criminal convictions or bad UK immigration history that the applicant has (i.e. refused visas/entry to the UK, illegal working or overstaying in the UK)
- a list of all the documents included in the package