Posted: 29/12/2013 at 13:45
I've divided your list into groups which may help.
These are generally problem/pest free so don't need protection when young: sweetcorn, celery, leeks, asparagus, runner beans, broad beans, peas, spring onions, potatoes.
These need protection from pests (main ones in brackets) and are best protected: parsnips, carrots (carrot fly), caulis, broccoli (caterpillars, woodpigeons.)
Of course, there are exceptions - leeks may be prone to leek moth for example but that's comparatively rare. Some things don't transplant well, so always sow direct (carrots, parsnips.)
Other advice I can give is to not start some things off too early, such as runner beans and peas; If there are late frosts like last year you will be unable to plant them out and will be left with leggy plants which will never crop well - later sowings always quickly catch-up anyway. If you grow Aquadulce Claudia broad beans you can sow them now and plant out on a mild day - they will survive frosts and snow to give you an early crop and can be replaced with your brassicas when they are ready for planting out. Plan the asparagus bed to be there for at least 10 years so prepare the soil really well and don't cut any spears in the first year and just a few in year 2.