What is this caterpillar please?

What is this caterpillar please?

Observation - What is this caterpillar please? - UK and Ireland. Description: This caterpillar was found just now at a cashpoint in town.It measures 6cm.I'd like to know what it will become and what it's ideal habitat will be.If it will be happy in our wildlife garden I will put it there.Thanks everyone(and hello from a newby). Th

This caterpillar was found just now at a cashpoint in town.It measures 6cm.I'd like to know what it will become and what it's ideal habitat will be.If it will be happy in our wildlife garden I will put it there.Thanks everyone(and hello from a newby).
Thanks,
Sarah