As a general rule, use seasonal fruit and veg, s this is when they will be at their best (as well as cheapest). Even imported fruit are best used when seasonal

January - Seville oranges (for marmalade) Mangos, anything apple based

February - not much

March - not much

April - you might get imported apricots, forced rhubarb

May - apricots, elderflowers, asparagus

June - strawberries, gooseberries, most UK soft fruit

July - tomatoes

August - tomatoes

September - blackberrys, elderberrys, apples, pears

October - apples, pears, sloes, blackberrys

November - sloes

December - seville oranges