you can get a viv what will suit it as an adult from www.rhinovivs.com there a bit more pricey than the normal viv but they look good, they will prob reach around the 5 foot mark maybe a little bigger. can be snappy, prob best off rreading caresheets ETC, there is also a chrondo book that is suppost to be like the bible for chrondo's
GTPs certainly aren't a beginner species, but depending on how much effort, time and money you are willing to put into learning about and providing the correct care, it would be possible to keep one as a first snake. They are usually snakes which people 'build-up' to keeping. Maybe consider an Amazon Tree Boa (ATB) as a snake to gain experience first.