Law has no specific subject requirements, so those would be fine! The english and maths combo is actually very strong. English shows your ability in essay writing, whilst maths is considered a science so you would be working with a strong skill set. As mentioned by the reply above, I would check if Oxford have any preferred subjects, as I know Cambridge considers English and History useful preparation. Also consider the possibility that you might end up changing your mind about law, so make sure your subjects would be ok for other courses you’d be interested in (for example you mention econ, in which maths is normally required, but further maths can also be useful). Unless you end up wanting to pursue a STEM degree, your options should be ok!