Second Life Tardis
Slamrket
That's one of the most common building projects for a new creator in SL. It's a good way to practice simple building/texturing/scripting skills. In addition to Emma's excellent suggestions, I recommend shopping around in Marketplace or, better yet, exploring in world to find freebie TARDISes that other people have made. There are a zillion of them and many are full perm, so you can see what they did.
Second Life Marketplace
Many are poorly made or use clumsy, outdated scripts, but that's fine. They will give you a feel for different ways to build. Sometimes you learn even more from a bad example than from a perfect one. (Please note: I am not recommending that you copy someone else's work.
Second Life Marketplace
That would be a violation of intellectual property rights and the Linden Lab TOS. I am simply recommending that you study and learn so that you can create your own version.).