Hi Nicos,

Honey bees tend to go for 'mass plantings' so this time of year all the tree blossom will be their main food supply if the weather is warm enough for them to venture out. Then comes rape seed, then borage etc. So I'm afraid they probably won't visit your daffs. Solitary bees will (should) but I think the larger bumble have problems getting in the trumpet. You might find holes at the base of the trumpet where the larger bees have pierced a hole to get at the nectar.
What I tend to plant on my allotment is Phacelia tanacetifolia (the green manure), lovely blue flower with feathery leaves. (I buy mine from Organic Gardening.) I stagger the showing through Spring, Summer, and Autumn and the bees love it - honey and bumble bees aswell as hoverflies. Its pretty hardy so will over winter and provide 'food' in early spring. When its finished flowering , chop it down and dig it in. You can let it self seed but then the plants pop up all over the palce!
Other plants I have tried with little success is clover and buckwheat - good for manure but I didn't see a bee within a mile of the stuff.

Hope this helps
cheers
Graham