Growing your rhubarb from seed would be a long term project. Even buying a crown it can take several years for it to establish and produce more than a few spindly sticks.

Thanks moongrower, I am aware that it's going to take time but I just wanted to know if I can collect seeds from the plants and what is the best way of doing this please?
Kind regards, John

John I honestly don't know but from what I have read you need to buy in seed rather than just using seed you have collected... Hopefully someone else can give you more advice.

It would be better to remove the flowers though if you want to go on harvesting the rhubarb for a while longer.
Can you beg a bit of one of the crowns in the autumn? If you are careful you may be harvesting a bit after two years though as MG says it will take rather longer to make a good flourishing clump.