The likelihood is yes, you'll have to self-isolate. How this will be monitored I haven't a clue at this stage. To date cafes have been take-out only, although that has simply meant tables / areas outside.
It'd be the same if you're on a club ride and one of the members riding has symptoms.
The only difference compared to March is there's now the facilities; the Nightingale's are there in statis. New staff are trained. Other, unannounced, facilities have been developed. For example SWMBO's Covid-19 rehab facility currently has 12 patients in. In March they had space for up to 16, but they were all occupied by patients with stroke/other disorders. Now there's space for 40 with 9 Covid-19 rehab in there already and only 3 for non-Covid rehab. The youngest is only 26.
The 'lockdown', which in many cases near me never actually happened, wasn't about removing this virus. It was about gaining time to build capacity to treat patients. Like others have put above I live in an ethnic minority town where cases are high. No meeting together? That's just been ignored by many. No hairdressers / places of worship open? Again ignored.
Do you know what's the word on the current capacity at the Mary Seacole rehab centre ? It's all gone quiet in the mainstream media and government never talks about it either.