Thank you all for these helpful suggestions.
John, I'll ask around my neighbours for suggestions of shrubs!
I hadn't heard of shade sails and have followed your advice, James, and googled them. I will look into these.
Gerald, thanks for the suggestion of bamboo. A neighbour has some growing in his garden and has invited me to go round to see it. I'll take him up on the offer. Thanks, too, for the advice to be sure to get a clumping variety.
Many thanks to you all.
