I first went out on a 100mm ht and had a blast you will be fine – Spare pads spare mech hanger , sudocream , Thicker grips.. and get some forearm workouts started now if you have a spare mech take it . if not buy one cheep on here ..
Guides are expensive unless you can split with a group but are a great way to get your bearings and explore early on in the holiday without thinking to much .. or you will just end up staying in resort.
If you dont want a guide or price wise it doesnt work follow the PPDS VVT route and explore early on in the holiday
http://www.ride-ability.com/ good guide i have had before – ask for quentin
Regardless of all this you will come back a changed man – its great out there dont think to much and just go and enjoy you will come back grinning