Woodland trust do a useful free app, you can use the 'decision questions' or a photo. Questions is good but you need to be close or have a leaf in your hand ideally, can't see things like fine leaf hairs on your photo. You can do it by Bark as well.
It doesn't ask if leaves are opposed or alternate but its a useful check when you do arrive at the answer. Yours look to be opposite, one pair sticks out from same place on stem. Alternate is when they come off the stem left-right-left-right. I thought your might be Bay Willow (is it at all boggy?) but they are alternate so likely not.
Anyway, woodland trust id app for android or ios, free, if you work through carefully it should get you there. Once you do get your answer read the species description carefully, you sometimes see things like "very rare only grows in ...." and you think hmmm, can't be that so start again.