Completely random question

I would strongly recommend going to a dive shop (maybe puffin dive centre oban) and trying on masks as a first stop. A well fitting mask is the most important thing as a leaking mask will make your time annoying. I started underwater sports over 20 years ago and still use the same mask as it fits so well, I've tried others but always go back.
Then the next thing to think about will be warmth and propulsion. If you get in to this and you're submerged in water for any length of time you're going to get cold quickly as you won't be swimming about hard to keep warm, I would probably go for a semi dry suit (effectively two wet suits over strategic parts of your body) and wetsuit boots with strap fins that fit over your boots rather than "pool fins" with the foot pocket. If you are planning on diving down to see some things you may want to consider a weight belt with a couple of kilos of lead to help but that can be easily added later.
The last thing is to learn lots about your local dive sites, easy entry/exit points, tide times (try diving at slack water to avoid potentially dangerous currents). Consider a surface marker buoy if you're diving somewhere busy.
Last but not least make sure your camera is charged and has plenty of space, tell someone where you're going and enjoy.