Small UK Garden Design

HI, I would like some designs made for the garden in the attached in the images.

I'm looking for designs for the central area circled by the low fence (redline) and a flat sitting area where the chair at the top of the rise is (yellow) along with a new fence in yellow - with UK with north of England acceptable plants, which should be perennial and low maintenance. The two areas could connect with steps etc.

As this will be a DIY landscape job, please keep costs and practicality in mind.

I have access to a digger, so the areas can be dug out, posts, fences, stone added etc.
The plan doesnt have to be 100% to scale etc...rather I would like to see nice ideas and plan of action etc.

I can supply lots more images including plan/ google view etc, and video to the winning designer. - Thank you for your interest.