A flowering climber with loads of nectar...

[Paul mabbott]

Some of the plants mentioned here are annuals in UK (Ipomoea, for instance) and some develop fresh growth each year and are not easy to maintain against a wall (Passiflora, for instance). Most of the climbers mentioned need either trellises to bind around or need their main stems attached to the wall! Some of these also need regular pruning.

Someone mentioned ivy - this would be my first choice - dense foliage for all sorts of invertebrates but also possibly for birds and amphibians; flowers which attract many nectar-feeders; and edible fruit.

Needs very little attention other than trimmming around the edges once a year.

[mrs fish]

This is the passion flower in my garden taken yesterday, it has stayed alive for two winters now and even the fruit has ripened this winter

[nightshade]

A couple of Honeysuckles with different flowering times could carry
right through the summer months, or one in spring and a later one
in summer there are several variations.
I also love my Grapevine it has a regular clientel of birds and insects
especially as the grapes ripen(mine is a small edible black grape)

[paddy]

I was just going to mention two honeysuckles - Lonicera P. Belgica and Serontina (early and late Dutch, I think are the common names) - very similar with staggered flowering times. Very easy to control, but need something to climb up. If against a wall, a few bits of plastic tube (like dead biros) to put long screws through can give you a bit of clearance for twiners. Or a repeat flowering climbing rose, with honesuckle through it...

[nightshade]

Good thinking paddy,I should have mentioned space them on a good trellis panel with blocks to hold them a couple of inches off the wall to allow birds to nest "in back"