3rd tone -- the throat grinder

[imron]

Tones are relative to each other for a given person, rather than being absolute values. You shouldn't be going outside your natural range to produce the tones, so if you find yourself doing this, perhaps the problem is actually that you are not going high enough for your other tones (and therefore in order to get the tone shift you are going too low on other ones).

[renzhe]

In addition to what imron says, Mandarin uses a contour tone system, which means that the absolute pitch of the tones shifts up and down together with the sentence melody -- what is important is the contour: flat, falling, rising, dipping, etc.

When it comes to throat issues, it can be caused by being too tense because you're concentrating on the melody and the sound. You get the same when you're first learning to sing correctly. It should go away after a while for most people. Just make sure that you're using a comfortable vocal range and then practice.

[realmayo]

If I try and pronounce words as relaxed as possible...I find that I really just sound like I am saying Chinese words in a full on British accent

It sounds like you may be referring to something I asked about in another post, http://www.chinese-forums.com/index.php?/topic/21170-sounds-from-the-mouth-or-throat/.