As for syndicate / share scheme - good if you can get it. I suspect it would be hard to find one that takes in student pilots - although in saying that, I'm in one.
Some syndicates like it as it keeps their aircraft in the air, and so the cost down for others... Schools don't necessarily like them as it could reduce their profits, and I suspect there are very few aircraft in the UK that are being over used. Much more likely to happen on the microlight scene I suspect.
The groups I know about would need a personal recommendation from a current member before you would be invited to join, so I'm not much help. I think there are at least 4 group owned planes at PF Club, two of which have had new starts in them recently, but both have close connections to other group members (both through marriage!). I have no idea about the flight centre.
It is worth looking at other places too (although Prestwick Airport is a great location). If you live near to where you are flying from, you spend less fuel in your car, you can look out the window to determine the current weather, and you wont have so far to go home if there is some reason that stops you flying!