We have access to core books only , including ph2. I have heard that since healing surges exist , a cleric is not that useful. However i may be wrong.
Do you mean just PH-1 and PH-2?
Leader options are Cleric, Bard, Warlord, and Shaman. Leaders are very good and having a leader is quite valuable for a party. I'd recommend avoiding the Shaman if you're new to the game; it's a complicated class to play.
I happen to like the flavor of Warlords the most. As mentioned, you need to be pretty tactically oriented and to enjoy giving teammates attacks/buffs. If you want to play a Warlord, Tactical Warlords are probably preferred to Inspiring Warlords with just PH 1 & 2. If your Rogue is a Dex/Cha rogue (as opposed to Dex/Str) and you play a Warlord, make sure the Rogue picks up Melee Training (dexterity) fairly early (Warlords grant a lot of basic attacks, which normally require Strength).
It sounds to me like you've never been in a party with powergamers that prefer most of their encounters around L+6.
It sounds like my character could beat up your character.