I’m definitely no expert, but as above, you need perennials, not annuals. Shrubs are also good, but you need to be careful re size of shrub vs size of your garden.
What you can plant and where depends on which way your garden faces and how much sun/rain different areas of the garden get.
A climber for the fence sounds a good idea, but what will grow there depends on which way the fence faces. Personally I’d choose something like a rose/clematis/Jasmine.
Re something for different seasons: for now you mainly want bulbs eg crocus, daffodils, snowdrops. Hellebores and polyanthus also flower in the winter.
Late spring/summer is easier as loads of things flower then. I like lavender, lupins, delphiniums (you can get a dwarf version), salvia nemorosa, agapanthus and roses.
For autumn, some of the summer flowering plants will flower into autumn (I still had flowers on my delphiniums in November), I also like cyclamen in the autumn.
Viburnum Tinus and ceanothus are nice evergreen shrubs in my opinion.
I’d advise against planting anything which self seeds like hell (unless you’re more diligent than I am about deadheading plants after flowering!) or anything which spreads out of control!
I’m not sure whether this is the sort of advice you’re after?
The gardeners world website has good advice about different plants for different seasons and the RHS website is really useful for finding out more about individual species of plant.