Medicines

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From a Search here. The requirement is original containers. The actual practice of many folks may differ. Safe travels.

I take pill bags. I ask the pharmacists to make a label for each, then attached the label to the bag. For OTC meds/supplements, I ask my hubby to use his handy dandy label machine to make labels. So I don't confuse AM with PM drugs, I use colored snack bags. AM pill bags go in green, PM go in red, Advil go in purple, tummy meds go in blue. All then go in my zipped pill bag. Easy to find what I need. The only things I keep in original containers are antibiotics and pain meds if I'm taking them.
I make a list of all my meds to keep in my suitcase, plus drug allergies. I also keep a list on the my phone's notes.

Technically, you’re supposed to take those bulky bottles with you. On over 20 trips to various entry points to Europe, I have always had them in zip-locks and never have been questioned about them. The only exception was when I had to take meds containing codeine. Even though it might be a long-shot, I’d never want to be found carrying any type of narcotic or listed drug without the bottle or pharmacy label.

We always use baggies for our meds when traveling. No problems ever entering countries in Europe, S. America or Asia.

Nobody really defines what an "original container" is, so actual form of the container is not the issue, identifying what the pills are, that they are for personal use, and they belong to you is.

It would be best to have labels on the bag, at the very least have labels or copies to be able to show, and more importantly, for reference at a Doctor if you somehow lose them and need more.

The one exception would be Opioids and Opiates or other strong pain meds, or if you require stimulants (which may cause other issues) Those I would have in a separate bottle, labeled, and only enough for the trip (which usually is not a problem since most are a 30 day max anyway).

True, no one will check, you will be fine, do not be too concerned, until they do check.

Unless the medicine contains a controlled drug you can do what you want

https://www.gov.uk/take-medicine-in-or-out-uk#:~:text=Bringing%20medicine%20to%20the%20UK,medicine%20was%20prescribed%20for%20you.