My 8 month old baby wont sleep through the night, can any1 help please ?x?

He goes to bed between 7 & 8pm we have a wind down hour to help him relax etc. He is just beginning to have 3 meals a day as well as his bottles so i am uming its ok to miss his night feeds. he normally wakes up at 3 and 4.30am for feeds then is up at 5.30 for the day. So last night for the first time i took water up instead of milk, but he was crying from about 1am every half an hour, i kept getting him out of the cot and offering the water, he would just take a sip and then snuggle into me and go back to sleep but every time i put him down he woke up half an hour later, am i right in keep getting him out of the cot to offer the water or should i put up with the constant crying by just leaving him inthe cot and soothing him, i really don't know what to do i am so tired at work and i dont have any energy to carry out a normal day i,e housework, work looking after kids, im so exhausted, has anybody got any thing else to suggest or shall i just stick to what i am doing? any help soo appreciated