Apart from being rubbish at the game, this is why I couldn't go on countdown.
The main problem arises in asking for the letters. What's the system here?
The first request should be followed by a "please" or a "please, Carol", Always. After that it gets difficult. If you want more than three consonants you're gonna sound stupid if you keep saying "and another", though if you purposefully try and mix up "and another" and "a consonant" then you're gonna get your pleases mixed up, which incidentally should be used at the end of every third letter request, unless the vowels and consonants have alternated for the past 3 requests.
And then you get to the last letter. Do you say thankyou? Do you end with ",Carol"? Do you say "and finally a..."?
It's a minefield.