the two classic fast growing flowering shrubs are Buddleia davidii and Lavatera shrubby varieties such as Burgundy Wine, Candy Floss, but both bush out to an extent. The Buddleia is the taller and thinner one, tending to go straight up and then arch outwards. Otherwise, Tamarix, which initially will be slightly bushy, but will rapidly grow into a small tree (though it can be pruned hard) but only flowers in Spring (although there's another one that flowers in late summer briefly). There are plenty of climbers you could use, such as Clematis hybrids, but none are particularly fast growing, although you may get flowers this year depending on the variety you choose and the size of plant you get.

Thats great. I think the Clematis is the answer. Many thanks. One more question, do I need to prune Clematis and how high do they grow?

Look up clematis on the A_Z at the bottom for advice and pruning.

Ah, well now, that depends which clematis you choose - they're in 3 pruning groups, so the viticella or jackmanii group, for instance, which flower summer and autumn, need pruning down to about 2 buds by mid February every year. The spring and summer flowering ones don't need pruning, although they can be pruned, and the spring flowering ones don't get pruned at all usually. These are the hybrid ones - the species clematis have slightly different rules, but all get much bigger than the hybrids anyway. You probably want one that doesn't get much over 6 to 10 feet, so a hybrid would be best. Decide whether you want a clematis in flower in early spring, or one that flowers early with large flowers and then again with smaller ones in mid summer, or one that flowers from about June until the first frosts, and make your choice, then prune appropriately. You can always ask if you choose one and aren't sure, but really, the important thing is to decide when you want it to flower. Examples from all three groups are: Nelly Moser (spring), The President (spring and summer) and Jackmanii (summer and autumn).

Thank you both for your comments, very much appreciated

You have good advice above. There is also pyracantha that will hug the fence with flowers followed by berries. There is also varieties of cotoneater with similar growth and flowers and berries like pyracantha.

I was thinking of pyracantha too - it is quite easy to train it flat with secateurs, with the help of a few canes or nails and wires. If you fancy the cotoneaster the one you want is horizontalis - in spite of its name it will grow as an upright fan against a wall or fence. It has tiny pink flowers and red berries. You could have a climbing rose too - choose the variety depending on which way the fence faces. (There are a few that will do well on a north facing fence) A yellow one looks great when grown together with a small flowered blue clematis.