We did manage to blag a stall in the courtyard of UCL last year. We can try again this year but if not there’s always Gower Street, not that that pseud Toni Negri will be worth listening to (or be comprehensible). Trouble is it clashes with our summer school in Birmingham, but not everybody goes there. Up to North London branch.
While the SWP do invite non-SWP speakers and offer space for non-SWP stalls (which the SPGB did last year), it clashes with Summer School except for the Thursday and Monday but there may be some London SPGB members attending, I don’t know.