Landscaping around a tree near decking?

[CaptainJack88]

I'm currently adding a mow strip/brick around the garden as you can see. So far i've got to the far corner and the edge of the decking.

As you can see in the photos below though, I have an awkwardly placed silver birch that the other half wants to keep, and we'd also like a water feature near the decking. Either on the left or right of the birch.

The problem I have is that I can't lay bricks near the birch due to the roots. Has anyone got any ideas how I can integrate this nicely into the decking area or a water feature?

 

[glasgowdan]

I'd let the lawn naturally flow up to the base of the birch, stop the edging at the end of the deck. Trees and grass shouldn't have concrete interfaces. The lawn still looks smart