If it is the bulb fennel, it is too late to use it in cooking, since flowering makes it tough and bitter. You might still be able to use the leaves as seasoning.

....and you can use the seeds in Indian cookery.

Thanks ,Nariz andTugbrethil,when do i sow it again?

I'll admit that I don't know when the proper time to sow it in the UK is--Here in the low desert, we sow it in fall to bulb up in the spring. It's probably the opposite in the UK. I would send a private message to Moon_grower, tell her approximately where in the UK you garden, and see what she says. She's the main veggie and herb guru for the UK, here in GoY.