The workload for year 10 isn't that bad, you may just have slightly more assessments than you did in year 9. My main advice is to do your homework to a good standard and when revising for topic tests make notes that you can reuse as this will save time in year 11 from having to make more notes and resources.
For a degree in medicine you need a solid set of GCSEs with mostly 7's to 9's. As long as you work hard for the next 2 years then you should be able to go into medicine.
Good luck for year 10 - I'm sure you'll do brilliantly