I find people's confidence that the 2m guideline will somehow protect them surprising.
It's like wearing seat belts when you drive.
Hugely reduces your chance of dying if you have a car crash, but doesn't reduce it to zero. Only way to do that is to never get in a car - but cars are really useful, so on balance of utility vs risk most people will drive with their seat belt. Similarly, most people will decide that getting out to buy essentials and maintain health through exercise is worth the risk, so long as they stay 2m away from people (wear their seat belt).
But you can drive safely or in dangerous situations. You're more likely to die in a car crash (even wearing your seat belt) if you're a) driving cross-country on narrow, twisty roads on a dark, rainy night rather than b) taking a short drive through suburban streets to the shop at 2pm.
Both are legal, but it's obvious that they're different, and you'll make your own judgement call about whether the more dangerous trip is advisable, maybe depending on whether the trip is to visit a sick relative (I'd risk it, but drive carefully) or to pick up a book from a friend (nah, I'll stay at home).
Similarly, you're much more likely to catch/spread the virus (even staying 2m from people) if you a) have a garden party over several hours where people move around admiring decorations and chatting in groups rather than b) go for a walk by yourself, occasionally passing others for a few seconds
It's OK to decide that the garden party is too risky for you. It's also OK to raise the risk with others, just like I'd ask my friend whether she really needs to make that cross-country drive on a dark rainy night, or whether it can wait until tomorrow. (Imagine how I'd feel if I was too embarrassed to ask her and then she crashed)
Tldr; there's nothing magic about 2m. We've been given a guideline, which is a best guess to reduce risk (based on limited information from the 3 months the virus has existed) but we still need to use our own brains and judgement.