Luke wrote:
I've started to collect seeds from flowers and plants that I have grown
this year eg petuinias, agapanthus, sunflowers, tomatoes etc. How should
I store these and do they need to be stored for a year before planting?

Cheers
Luke
Try storing them in brown paper bags with tissues, (Pay envelopes are
ideal, as they used years ago,from office supply business) and keep them
dry.
Also add some bordaux powder to the seeds, will help prevent fungal
disease when planting them out.
You shouldnt keep seeds any longer than necessary, but some keep better
than others. The new planting season is best.