GCSE

Nope I believe it's all good. Most important thing to do well in paper 3 is to memorise your fieldwork and just general fieldwork skills (e.g. types of gathering data, systematic, random). It's important to know things like risk, and why your fieldwork was done how it was, know about different types of data representation, like pie charts, etc.
It's also really useful to understand how to write well, to do well in the 9 marker and such at the end on your own fieldwork, e.g. having your main point and being able to back it up. Past papers are good for this.
Finally it's definitely worth polishing knowledge of paper 1 and paper 2 because you can need to draw knowledge from that in section A, generally knowing the vocab and also knowing question command words. For example, a lot of people get caught out on questions like 'justify your data sampling methods' and put about what they did, but what you need is to show why this helped your results.

Loads of resources online if you care to look, the mark schemes and examiner reports are really useful!

Hope this helped slightly . Good luck!

I'm also resitting my geography GCSE exam next year (privately) and was wondering if I can use the same fieldwork I used last year or can I use one I've found on the internet?

I'm pretty sure you can use any, so long as you put the title down and such. The Geography Fieldwork evaluation thing that teachers fill in is just to say that you've done fieldwork, which notably you have, so you should be able to do whatever you like, using a different one to the centre shouldn't make a difference (it's quite common for home-schooled students to just make it up because it's harder haha, and that always goes fine).

Best of luck once more! Hope that helps

That's good thank you so much for response