What fertilizer would you recommend, when and how to apply it, please.
I got one "Bulb fertilizer" from Brecks - is it good for all these plants, please?

Any reputable agronomist will tell you that if you garden where the soil has not been compromised (mining/waste tip/oil spill/chemical spill - you get the idea) then you do not need to fertilize perennials. If you are growing vegetables - that's a whole other thing. You may choose to add something to the hole when planting bulbs.
I have never fertilized my perennial garden in the 40+ years we've been here and it is still as 'productive'

I do fertilize in early spring but with nothing special. I get a couple bags of balanced cheap nothing special fertilizer and throw it in the general direction of the garden.

Dear Vals,
Last year I did not fertilize tulips and hyacinths, but they look much better this spring!
From now on I stop fertilizing them and peonies.
How about lilies?

I don't fertilize lilies either

Hyacinths, tulips, crocus, spring bulbs in general, always do better with more dry summer heat when they are dormant. Of course it depends on the type of soil you start with, but less (or no) fertilizer will likely encourage better flowering and smaller plant bulk overall. If you had a hot summer and no fertilizer, then your success is a result of both.

Fertilizing will make most perennials grow faster and more lush (what regular people want), but usually not any more healthy. With more fertilizer than they need, they can be more prone to diseases and insects, and may have a shorter lifespan, too.

I fertilize pot grown materials, but rarely in ground. The two soil environments are very different.