Pigs On the Wing Pt. 1 (Strum Pattern)

Hi all. I am a big Pink Floyd fan who has recently taken up acoustic guitar. I've been trying to learn to play 'Pigs On the Wing Pt. 1' (it is only the second proper song I have tried to learn, the other one being a Greenday *shudder* song my former guitar teacher suggested), and I am having some (well a lot of, actually) trouble figuring out the strum pattern.

I have been playing the first half or so with what sounds like roughly the correct pattern, but not quite. This being (not sure how I'm supposed to write this but I'm sure you can work out what I mean)...

G.................C
D--UD-D--UD-DUDU repeat

I've been playing like that up until it changes to an A chord, and from there I have no idea. I've searched quite thoroughly on the net and tried to figure it out by ear, but haven't been able to get anywhere. I would appreciate it greatly if somebody could explain it in such a way that a novice like me would understand.

Also, I dl'ed the 'Animals' e-book, and it uses the chord sequence G, C, G, C, G, C, G, C, G7, C and so on, whereas all the tab I have seen on the net uses Csus4 in place of the G7. I've been playing it with the G7 but it really doesn't sound right to me. What is the correct sequence?