Schools Direct or similar in-school ones are generally seen as more stressful, and throw you in at the deep end a bit more! PGCE is more academic (more essays!), but still with lots of school-based experience.
I went from work into a PGCE and for me it was the right option - it was a slower start into school with time in college to get my bearings before the first placement, and then chunks out of school to -recover- be a student. And having the support of the university was very important. Downsides were that you don't know where your placements will be until about a week before, and they could be quite far! My schools were very different from each other, which was a good thing to see so early. My uni also had a 2-week 'alternative' placement in the middle, where you could go to a special/forest/private/nursery/foreign school.
School Direct - especially the paid ones (they're not all paid)- are competitive to get on, too. Some of them are run by universities and some by schools or groups of schools. Some people love it, and they often have a job at the end, I just know it wouldn't have been right for me. It can also be limiting in terms of the experience because often you'll be sent to nearby, similar, schools for your second placement. But if you have a lot of school experience and feel ready to hit the ground running, it can be great.
I would say in terms of your experience now to definitely try to get whole days in. You'll need to have 2 weeks experience to apply anyway. Try to work with different children, not just the ones who need a lot of help who they might put you with!
Also try to get in to different schools. Schools vary hugely, and I really think it helps to have seen as many as possible. The two schools I trained in were very different from each other in ethos and intake, and the one I now work in is different from both of them! I know some people who worked in terrible schools and thought they hated teaching, but it was because they'd never seen anything else.
Good luck! It's the best job in the world, even when it's a bit shit 