If you are applying to Medicine in the UK you will need to apply as an Early Applicant through UCAS before 15th October.
Many universities require you to sit one of these tests.
UKCAT (Closing date September 23rd, GOPAS SR Bratislava, Centre International Universitaire Vienna)
BMAT (Closing date September 30th, British Council Bratislava)
Non UK options
Other useful links:
NHS Clinical Knowledge Summaries
Gap year medical programmes