I was in the same position. RTE London: I wrote a letter to them from myself the company MD explaining what the company did and how it allowed me to work remotely.
Get a visa cancellation letter from your University and get it cancelled at immigration as that's what they ask for. An extension of stay is also part of the visa (if you have one) as you can't have one without the other.
i've never used wise as there are better UK exchanges with better rates. Consumers would be protected under FCA regs if they chose a FCA reg exchange also.