Not an expert here, but currently working on NTP for our production environment...
Timezone is set when you set the locale of the ESXi host during installation I believe. The time, when using NTP is provided by the NTP source. Here in the UK we have this GMT+1 thing going on, so not dissimilar to you. So, a Windows server for us gets NTP from the internet (that server has correct time zone etc), and our ESXi servers points to the Guest server for NTP (along with everything else). Most organisations use their internet gateway/proxy/firewall to provide what I call authoritive NTP. In the end, the ESXi should report the correct time for your zone provided the time source (in our case a Windows server) is setup to provide NTP as a source and has the correct TimeZone info.
I hope that helps - just chipping in since I'm looking at similar stuff myself now.