Where to hold my emergency fund?

On track to have a 40-50k emergency fund / cash buffer as a safety net, as I'm self employed etc.

I specifically want to keep this cash away from volatility as I might well need it during a financial crisis etc, and I'm long on various other things. Clearly an ISA is tax efficient and right now it's cash in an IG stocks and shares ISA. Historically I'd have put this in a ETF like a S&P 500 one, but in the current climate feel that's not where I want my 'go bag' (plus I'm already pretty long on the US in my sipp).

My first thought was a mid term gilt like TR28 but can't seem to buy that in the IG ISA. Where worst case I'll get back the money, less any premium I paid, plus the coupon value.

No debt outside of mortgage, cars all owned outright etc.

Thoughts?