Farmed and frozen game provide a supply of game all year but most wild game is only available during the shooting seasons, which vary from animal to animal. Game cannot be shot outside these seasons.
Here are the seasons for the main varieties of game (although there are variations between foreshore or inland for some water fowl):
Ducks and geese - 1 September to 31 January; 
Hare - 1 August to 29 February;
Grouse - 12 August to 10 December;
Partridge - 1 September to 1 February;
Pheasant - 1 October to 1 February;
Pigeon and squab - all year;
Quail - all year;
Rabbit - all year;
Snipe - August to January;
Woodcock - October to January;
Woodpigeon - all year
Venison: Red deer stags - 1 August to 30 April (England, Wales, Northern Ireland),
1 July to 20 October (Scotland);
Red deer hinds - 1 November to 28 February (England, Wales, Northern Ireland),
21 October to 15 February (Scotland);
Fallow bucks - 1 August to 30 April;
Fallow does - 1 November to 28 February (England, Wales, Northern Ireland),
21 October to 15 February (Scotland);
Roe bucks - 1 April to 31 October (England, Wales),
1 April to 20 October (Scotland);
Roe does - 1 November to 28 February (England, Wales),
21 October to 31 March (Scotland);