It is a Geum, but I do not know which species. Leave it until it flowers and then see if you think it is worth keeping.

Thank you. Now I've got a basic name I can maybe narrow it down a bit more. I vaguely think it had small white or yellow flowers.

if they are small yellow ie 2-4 mm across then it is a wild version and usually considered as a weed. if they are 10mm or more then it is a cultivated variety and if you like them worth keeping.

Yes, Herb Bennet or Wood Avens (Geum urbanum).