blue shrubs

There are only a few shrubs with blue flowers and even fewer that would be able to tolerate coastal conditions.
A small hebe (such as 'Autumn Glory) would be suitable. If sheltered from the worst of the weather, lavender would also grow well

I have spent some time checking this one out and agree with Andrew - there are very few blue-flowered evergreen shrubs. I found Hebe 'Mrs Winder' (A.K.A. 'Waikiki' or 'Warleyense'), Teucrium fruticans - silver leaved with pale blue flowers and Ceanothus species - there's thyrsiflorus repens which is a spreader, or 'Burkwoodii' which could be kept back to your 3' with pruning. (normally grows to 5') Hope this helps. P.S. If the soil is too chalky, the Ceanothus would unfortunately not thrive - they'd become chlorotic (yellowed leaves, needing treatment)

Teucrium can be pruned hard, if not it gets very big.