The guidance is clear.I feel that riding with others (not from the same household) is stretching that eased guidance to its absolute limit and isn't particularly responsible... IMO it's more aimed at meeting up with say, a family member or a close friend that you haven't seen in months.
It's all well and good quoting this "magic" 2 metres that the virus apparently can't cross, but as a cyclist you still need to be fully aware of how far virus can be carried in someone's slipstream. No point quoting 2 metres which is based on being stood still in the open, and then riding at 20mph and expecting that to hold true. You can't avoid risk completely of course, but you can reduce it so I'm happy to ride solo or with family for quite a long time yet. I don't see any real need to actively test the boundaries of the issued guidance.
You can meet up with any one person as long as you distance.
Any belief that transmission is somehow more likely cycling than walking or sitting is, at best, speculative.
Any suggestion that it only applies to close friends or family is incorrect.