Warning, personal opinion:
Universities don’t necessarily want to see portfolio work in the area that you’re applying for. They want to see that you’re someone they can teach the course to and you’ll achieve a good result for them. That means they don’t necessarily care if you took CS at A-level, but instead are more interested in if you’ve got a good foundation (which for CS means good Maths results, and additional sciences help too).
Alongside that they’re interested in seeing people who can teach themselves, and who have enough determination to not quit the course after a year. This is where your personal projects come in - emphasise quality over quantity - don’t have tens of little games that aren’t polished, try and focus on one or two bigger ones that you’ve worked on for quite a while.
If all else fails, be nice. People reading/interviewing for uni places are human too. ;D