Trinity College Wesley guest accommodation is a 10 min walk to the School of Chemistry and Biochemistry. Currently, there should be about 30 rooms available. Please let me know via email  if you need help with arranging your booking.
St Catherine's College accommodation is a 15 min walk to the School of Chemistry and Biochemistry. Unfortunately, this accommodation seems to be rather full at the time of the conference, nevertheless, it might be worthwhile checking...