Hi Love,
A tip I learned a long time ago for leaking threads on pots is Plumbers tape. It is called PTFE and you can get it at B&Q It is a self amalgamating white tape and will work great for a short term fix but I would strongly suggest getting a new pot. You dont want to go to clients or have them come to you and see a tatty taped up old pot. LOL also the white tape will look nasty when the solution stains it. It is better to replace the tape after every tan until your new pot arrives.
When you get the tape, put your solution in the pot, the firmly tape all around the "thread" area, pulling it along firmly enough for the tape to stick to itself. Do a few layers ( one wont be enough) probably 4 or 5. Screw lid on and away you go.
Hope this helps