I'd suggest getting some of these.
Atelier Rorona (slow start, but it is immensely addictive.)
Atelier Totori (you should play Rorona before this, but its graphically better and the gameplay is improved.)
Cross Edge (pretty good 2D based game.)
Disgaea 3 (you can get it for around £8, its a grinding tactical grid game, i found the plot boring though.)
Hyperdimension Neptunia (awesome game if you like dungeon crawlers.)
LA Noire (its basically heavy rain and GTA combined.)
Prince of Persia Forgotten Sands (great game, but a little short.)
Silent Hill Homecoming (found it enjoyable)
Siren Blood Curse (annoying when you can't kill the enemies at times.)
Trinity Universe (a slower version of HDN, but still good.)
and wile its not a ps3 game, they do work on the ps3.
Persona 4 (a fun game.)
Shadow Hearts 1 & 2 (SH1 was originally considered to be Silent Hill the RPG and its an amazing game.)
Shin Megami Tensei digital devil saga 1 & 2 (you can buy both of them for about £9, tremendous story and the only thing I don't like about it is that in human form, you can't use magic.)
Shin Megami Tensei Lucifer's Call (dungeon crawler with a good story and it has Dante in it as a recruitable demon.)
Shin Megami Tensei Devil Summoner 1 (very similar to Crisis Core.)
But, if youre in the UK, there should be a Graingergames relatively close to you, they import games from america and they already have MGSHD in stock for £35.
As for Assassin's creed, I was given the first, second and brotherhood and I played half of the first one (waaaay too repetitive) and the other two, I finished them, but I didn't do the 100% playthrough or even found myself compelled to.
(and I spent like 5 hours looking for the codec pages in the second one because I didn't get them during my normal gameplay.)
but, storywise, you can read a symposis of it online and get the exact same debriefing as you would playing the game properly.
but, assassin creed 1 in a nutshell.
Altair is a total jerk, he breaks several sacred rules of the brotherhood; he's demoted down to a rookie and he has to kill 9 of their greatest enemies.
for each one he kills, he's rewarded with a new skill and piece of equipment, and its the same deal every time you hunt one; go to the town, look for the guild, get told wh you're killing, then yu interrogate people or pickpocket them until you have enough information to actually kill the target.
you kill the target, then you return to the base, get praised, then do it again.
for the last one, we're mislead on where he is, and then we manage to kill him after about an hour of added gameplay, when we return, it turns out the leader is abusing the apple of eden (very important item, it has magic powers) and is now trying to kill you.
after you kill your leader, Altair takes the apple for himself and uses it to make devices hundreds of years more advanced than their level of technology and becomes the mini leader basically.
We find out the people who kidnapped desmond wanted to look in his dna memories to find out where the apple of eden is because his descendant had it.
They tried to look in the memories of someone else, but they pushed him too hard and he started to visit his ancestor's memories in the present day without the machine and killed himself.
thats pretty much all you need to know from the first one to fully enjoy the second game.