I found this list while looking for Gladiolus growers/suppliers. I thought it might be useful for others.
http://www.thegardeningwebsite.co.uk/specialist-nurseries--growers--and-plant-suppliers-c412.html
The garden centres we visit always have bags of bulbs hung on racks, Taylors are the main one here. I found they have a retail site called Walkers. There you will find the whole range, not just what the garden centre wants to stock. Many varieties of Narcissus if you are looking for those extra special ones. They can also source other bulbs not listed. I hear the complaints of paying postage, free over £40 if you want to place a good stock-up order. Petrol can cost more than postage if you have to travel distances or make several trips.
The autumn catalogue is valid at them moment, the spring one should be available in the early New Year. Online ordering top tab.
http://www.bulbs.co.uk/1/default.asp
Specialist Nursery links.
The first link has stopped working for some reason, even when I typed in the address it came up as a domain website advert. I have it in my favourites, it's still fine there, I will try to place a link to the category page.
http://www.thegardeningwebsite.co.uk/category.do
If anyone is interested in growing top quality show gladiolus I found this,
http://www.showglads.com/
There is also a link at the bottom to daffodils, some rare and expensive ones there.