french gcse

I never did a proper gcse speaking as my year's exam was a bit weird but I can give you some advice from my a level structures that I think are plausible for gcse students.
Examiners adore 'Si' structures and there are different types you could look up. This seems to explain it decently well: https://ai.glossika.com/blog/conditional-phrases-and-si-clauses but if you don't get it you can find other websites/videos.
An example you could use within the vibes of your topic is:
"Si j'étais médecin, je pourrais aider beaucoup de personnes malades." = If I was a doctor, I could help lots of sick people

If you've learnt the subjunctive, I'm sure the examiners would love that but if you haven't, I wouldn't bother with it as it's too complicated to waste time on now.

Try to use lots of tenses. Since you're talking about the future in terms of career and not what you're doing next weekend, avoid using the near future (aller + infinitve) and use the proper future tense (j'irai, nous ferons etc). I would also try and slip some past tense in there eg:
"Il y a 2 ans, je voulais devenir acteur/actrice mais maintenant j'aimerais etre médecin." = 2 years ago, I wanted to become an actor but now I would like to be a doctor.

Use interesting opinion phrases: Je crois qu, je suis sur que, je suis convaincu que, il est évident que, selon moi, d'apres moi etc.

Use interesting negatives: ne...rien, ne...que, ne...aucun(e), ne...jamais eg:
"Je suis intéressé(e) par la politique mais je n'ai aucune envie de devenir politicien. Je ne veux que etre médecin." = I am interested in politics but I have no desire to become a politician. I only want to be a doctor.

One last thing, since your topic is your future aspirations. it's easy to fall into the trap of only using 'je' the whole time but please try and use other pronouns. Talk about would your parents want you to do in order to use 'ils'. Pretend some of your friends want to do the same career as you to say "Nous voulons tous devenir médecins".

Good luck!