I am looking for similar. Single-trip policies are very expensive. I found an annual policy with LV that would cover 90 days but if you include flights my trip would be 92. They refused. This means only single-trip possible and the cheapest quotes I have found for 92 days are around £300.
I was in a uk bank this morning pre-warning them I wanted a large amount of cash in unmarked notes next month for Thailand. Actually this had not been so much of a problem since we switched to plastic notes, but the bank said they would no longer check the condition but that I must do it and then take any unsatisfactory notes back to change