A smaller than average Clematis armandii (evergreen climber) is Little White Charm, listed on this page:
www.clematisplants.co.uk/clematis-spring-flowering.htm
the usual ones are quite vigourous.
Clematis Early Sensation and cirrhosa are also evergreen, you will find them on on the above website.
Another lovely evergreen climber is Trachelpsermum which flowers over the summer and has the most amazing scent. I find Jammine a bit messy as a climber, ok if you have loads of room but often looks a bit of a tangled mess if its on show.
Re evergreen shrubs, I think Portuguese Laurel is one of the best evergreens, smart glossy leaves, not fussy re soil type, wind and drought tolerant, fairly fast growing and flowers in summer. There is a thornless Holly which I have in my garden and it looks great, Ilex JC van Tol. Choisya is another good evergreen choice, Aztec Pearl is the prettiest with lovely white scented flowers.
This is a climbing (rambling in fact) rose which is thornless but its not miniature, is more or less evergreen but needs a sunny spot
www.classicroses.co.uk/roses/r/rosa_banksiae_alba_plena.html
The best Magnlolia for a pot would be a Magnolia stellata, the others are too large
www.burncoose.co.uk/site/plants.cfm?pl_id=2808
I'd probably put in some decent small trees/shrubs and climbers first and then add perennaials later on.
My favourite small tree is Forest Pansy
www.jacksonsnurseries.co.uk/plantcard/CercisForestPansy/1065.aspx which needs a sunny spot.
For shrubs, there are lots of good Viburnums, some evergreen and some scented, V burkwoodii is both, Choisya,Deutzia and Hydrangea are easy shrubs for summer/autumn flowers.
Good climbers are clematis (as above), Akebia, fast and easy to grow and semi evergreen, Solanum jasminoides which flowers from spring to autumn and grows quickly.
HTH