Looks like Goat Willow (Salix caprea) to me. Would treat it like a weed. Not suitable for gardens.

Hi Jimmytheone , thank you for your reply. I’ll bin it lol. I’ve no idea where it came from!

It is one of the most frequently seen self seeded trees that there is. The seeds are tiny so they can arrive from anywhere in the vicinity.

Owdboggy, thank you for your answer.