Too early for flower buds to be showing yet. Give it another month or so. Resin

"Could this be causing the problem?" Very possibly, yes. Don't use pesticides or herbicides, without a verified, identified need. Even better, not at all, ever. Resin

I can't tell you where to get them (I'm waaaaaay far from you), but I do have half a dozen or more of them in my yard, so I can tell you a little about them. They are gorgeous right now, as they make a stunning curtain of yellow in that part of the yard. The spent flowers (no longer golden chain: think grey chain) are a bit ugly - on my trees anyway, they stay on the tree (last year's are still there while this year's have almost hit full bloom). I've read tips like "remove seed pods" (they are poisonous), but these trees are BIG, so there will be no removing seed pods for me. The seeds that do drop sprout up everywhere (the way wee maple seedlings do), but are easily dealt with by mowing the lawn or plucking from the garden.

Just a caution. As I recall, laburnum seeds should be kept away from children, as they can act like a drug, if ingested.