If you are going to fly the Duchess one of the best training aids is the King schools multi engine DVD. It applies for other twins of course but they use a Duchess in the DVD and although they are American the twin stuff is pretty much universal.
I found the DVD gives a good basic grounding in the subject, then add in a generic twin book such as 'Transitioning toTwins' and of course the flight manual for specifics on your actual a/c.
You can get a copy of the King DVDs in the UK from Transair - but its not cheap, about 60-70 squid!
As for your relative 'Greenness' - who cares?! Do what you want to do. Of course you need to be sharper, more professional and more switched on to fly twins than you do to bimble round the local area in a 150 but so what? Either you can or you cant but you wont know unless you do it!
.............Also if it turns out you cant handle it now - Do it later!
Regards
Xraf
