we go every year but dont take any injections, just only drink bottled water, its cheap enough in the local supermarket.
My advice is do not take the malaria tablets they make you so ill, our pal did & had diarrohea for the first week before he told us, we advised him to stop and he was better within 24 hrs. Just make sure you have plenty of mosquito repellent- Boots do a good roll-on one, a de-stinger in case you get bitten and ask the hotel to light mosquito a coil in your room before you go out for the evening or buy a spray in the local supermarket. If you have paid for a room with a/c you will be more comfortable at night.
Dont forget to visit the spice fields whilst there, forget going to any crocodile tours they are full of swamps & mossies.
All pharmacies over there sell tummy upset tablets amd no prescription are needed for any medicines just ask the pharmacist[ even viagra !]
enjoy your holiday, everything is so cheap out there..
my one bit of advice, when you get to the check in, ask are there any premium seats left and if so pay the extra for them, on a long journey you will be glad you did.