Where can you get information about transposing instruments and where they transpose to?

And what are the chords needed for grade 8 theory?

Thanks

The Blue theory book (Part 2) published by the ABRSM will tell you everything you need to know about transposing instruments.
I would suggest getting the Grade 8 theory workbook as well.

The syllabus is on the main ABRSM site.

Always consult the syllabus. Read and re-read it for its precise requirements.

I endorse what Daisy duck has said about the Workbook and Blue theory book, you proably need a good HRmony book too. Dorothy Pillings comes Highly Recommended. For transposing instruments try Walter Piston Orchestration; this will be useful elsewhere. And the recommended default text on Music History is Grout/Pallisca A History of Western Music.

There is some good information on the Dolmetsch site ; it would be worth a look, I think it covers transposing instruments.
I'll check the web address and post.

http://www.dolmetsch.com/theoryintro.htm

try chapters 19 and 26 (I think), which deal with transposition and transposing instruments

Do you mean the AB guide to music Thoery Part II by Eric Taylor?

Yes

There's also the Adler Study of Orchestration. Very expensive, but very good too.