I’m in shielding also for immunesupressants and have continued riding since the lockdown. The advice was ridiculously strict but had to be becuase of the whole ‘caution contents are hot’ society that we live in. Someone even went on the BBC to say if you can go outside and guarantee you don’t go near anyone then thats fine. At the end of the day if the advice is you should isolate but if you live with someone just make sure you’re 2 metres away then I’m pretty sure I can continue to ride a bike alone.
I have to say going out during lockdown was actually better than it is now, we did 40 miles Sunday and the amount of cyclists and walkers on the roads we encountered who refused to move 2 metres away was mind boggling. Great that they’ve made the deicison that it’s safe enough to pass people closer than 2 metres however, I haven’t made that decision!!
If for some reason you decide to go out with others (you’re technically now allowed to meet one other person under our shielding) I would warn you that they likely won’t respect or stick to the distance so I would either have a serious word with them or just stick to solo for now.