Uk STamps to germany

[hasenaali]

Hi Im writing a letter to Britney Spears Via Venue to germany

How Many Uk 1st class stamps should I send to Britney along with a 4x6 envelope, and A4 (But Folded) letter and a A4 (but folded) poster?

and should I just write ''By Airmail and Hold until 26th July'' and just simply post it in the letterbox like I normally do in the Uk?

Thanks!!
xoxo

[beecs]

a5 is 56p
a4 i think is 72p