Aside from specific platform and broker choices, I would recommend you to start with a demo or cent account. It doesn't prepare you for all aspects of trading but it is great to get the hang of the trading process and practice your skills.
The answer will be different if you're intending to trade large options at volume, occasionally buy shares in companies outside UK, or looking to optimise tax as examples.
Ignore recommendations from strangers on the internet who tell you to use ABC without asking what you're intending to use ABC for.