YES, of course your sweep can visit during a lockdown. Restrictions don't apply to tradespeople carrying out work, it's friends and family that are restricted. BUT .....
“JUST OUTSTANDING”. That’s how Guild of Master Chimney Sweeps chairman Lawson Wight described the way professional sweeps are meeting the coronavirus challenges head on.
If you try to burn sawdust on your stove or open fire you'll be disappointed. It will tend to smother a nice fire and produce lots and lots of smoke. That's a pity if you have lot's of waste sawdust.