You can change your HOL Name only for a valid reason, for example if you accidentally put your real name. Please do not ask for a name change just because you don't like your current one anymore.
A name change produces a lot of work, everything from your student file, to your forum and common room accounts etc. has to be changed. Send an owl to your Head of House which includes a reason for the name change, your student-ID, old HOL name and new HOL name (or old email address and new email address, if that is what you're changing). Send the owl from the email address you've registered with, or it can't be changed (anyone then could ask to change your name without your approval).
You can change your Email Address at any time from within your profile. Do not forget to change your email in the HOL Forum as well (click on 'MyControls' in the menu bar). Please also email your house prefect, so your address can be changed for your house newsletter, Common Room etc.