Do a 15-20min boil with 20g Tettnang, turn off stove, add another 20g and put the lid on. Sit for 10mins. Strain through a sanitised sieve into your fermentor. This should only add maybe 5IBU's plus some aroma.
Steep the carapils at 66C for 30mins and strain also.
I did this kit not long with kit yeast at about 12C and found it to be a little fruity for my liking. I would suggest S-189 at 9C for a really clean flavour.