No solo without Air Law.
Well, let's see - I first did it back in 1990 with a UAS (probably not covered by civvy regs), then I did it again in the US while building hours during ATPL training. Racked up at least 30hrs solo before coming back to the UK and sitting ATPL Air Law exam (along with all the other 'practical' flying exams - Met, Gen Nav, Radio Nav, Flight Planning, VFR Comms, IFR Comms, oh, and the RT licence).
Perhaps you need to clarify the exact circumstances you would be applying this restriction to.