Thanks for the detailed answer.
Working backwards, I have been away from the UK since 2010 so the ISA wouldn't be an option. Technically I shouldn't have a UK bank account either but I've just kept it under my in-laws address and stayed schtum.
I was previously using Currencies Direct but found they were pulling my pants down with the rate so have switched to Wise. They are showing the actual figures which will be transferred in the receiver currency so I know I'm getting a much better rate than CD. The problem I have is that Peru doesn't inspire many financial firms in that Wise, for example, won't let me transfer money to my account with them but will facilitate a transfer between Euro or UK banks to Peruvian bank account so I need to decide which way to jump rather than hold it with Wise and watch the rate.
It's the potential need to exchange again from UK to Peru but I feel it's probably the safest bet to fire it to the UK. If a Kwarteng/Truss type announcement could happen this week in order to make the pound freefall that would be great. Thanks again for your help.