January

New Year's Day Parade (1 January)
Chinese New Year 2012 (23 January)
Burns Night (25 January)

February

RBS 6 Nations (4 Feb - 17 March)
Valentine's Day (14 February)
The Great Spitalfield's Pancake Race (21 February)
Carling Cup Final (26 February)

March

St. David's Day (1 March)
Cheltenham Festival (13 - 15 March)
St. Patrick's Day (17 March)

April

Easter (6 - 9 April)
The Boat Race (7 April)
Grand National (14 April)
RHS Flower Show - Cardiff (20-22 April)
London Marathon (22 April)
St. George's Day (23 April)

May

FA Cup Final (5 May)
Royal Windsor Horse Show (9-13 May)
Ten Tors (12-13 May)
MoonWalk London (12 May)
Olympic Torch Relay (19 May - 27 July)
RHS Chelsea Flower Show (22-26 May)
Royal Bath and West Show (30 May - 2 June)

June

Run to the Sun (1-4 June)
Epsom Derby (2 June)
Queen's Diamond Jubilee (2 - 5 June)
Rockness (8-10 June)
Download Festival (8-10 June)
MoonWalk Edinburgh (9 June)
Royal Highland Show (21 - 24 June)
Isle of Wight Festival (22-24 June)
Eden Project Sessions (23 June - 11 July)
Yeovilton Air Day (23 June)
Hackney Weekend (23-24 June)
Wimbledon (25 June-8 July)

July

RHS Hampton Court Flower Show (3 - 8 July)
T in the Park (6 - 8 July)
British Grand Prix - Silverstone (6 - 8 July)
The Royal International Air Tattoo (7 - 8 July)
Latitude Festival (12 - 15 July)
Hard Rock Calling (13 - 15 July)
Cambridge Folk Festival (26 - 29 July)
London 2012 Olympic Games (25 July - 12 August)
Olympic Games - Opening Ceremony (27 July)
Olympic Games - Archery (27 July - 12 August)
Olympic Games - Athletics (27 July - 12 August)
Olympic Games - Badminton (27 July - 12 August)
Olympic Games - Basketball (27 July - 12 August)
Olympic Games - Beach Volleball (27 July - 12 August)
Olympic Games - Boxing (27 July - 12 August)
Olympic Games - Canoe Slalom (27 July - 12 August)
Olympic Games - Canoe Sprint (27 July - 12 August)
Olympic Games - Cycling - BMX (27 July - 12 August)
Olympic Games - Cycling - Mountain Biking (27 July - 12 August)
Olympic Games - Cycling - Road (27 July - 12 August)
Olympic Games - Diving (27 July - 12 August) 
Olympic Games - Equestrian (27 July - 12 August)
Olympic Games - Fencing (27 July - 12 August)
Olympic Games - Football (27 July - 12 August)
Olympic Games - Artistic Gymnastics (27 July - 12 August)
Olympic Games - Handball (27 July - 12 August)
Olympic Games - Hockey (27 July - 12 August)
Olympic Games - Judo (27 July - 12 August)
Olympic Games - Modern Pentathlon (27 July - 12 August)
Olympic Games - Rowing (27 July - 12 August)
Olympic Games - Sailing (27 July - 12 August)
Olympic Games - Shooting (27 July - 12 August)
Olympic Games - Swimming (27 July - 12 August)
Olympic Games - Synchronised Swimming (27 July - 12 August)
Olympic Games - Table Tennis (27 July - 12 August)
Olympic Games - Table Tennis (27 July - 12 August)
Olympic Games - Taekwondo (27 July - 12 August)
Olympic Games - Tennis (27 July - 12 August)
Olympic Games - Triathlon (27 July - 12 August)
Olympic Games - Volleyball (27 July - 12 August)
Olympic Games - Water polo (27 July - 12 August)
Olympic Games - Weightlifting (27 July - 12 August)
Olympic Games - Wrestling (27 July - 12 August)
Olympic Games - Rhythmic Gymnastics (27 July - 12 August)
Olympic Games - Trampoline (27 July - 12 August)
Camp Bestival (26 - 29 July)

August

National Eisteddfod (4 - 11 August)
Boardmasters (8 - 12 August)
Bristol International Balloon Fiesta (9 - 12 August)
Edinburgh International Festival (9 August - 2 September)
FA Community Shield (12 September)
The Perseid Meteor Shower (12 - 13 September)
British Firework Championships (14 - 15 September)
Beautiful Days (17 - 19 August)
Manchester Pride (17 - 27 August)
V Festival - Hylands Park (18 - 19 August)
V Festival - Weston Park (18 - 19 August)
Carfest South (25 - 26 August)
Reading Festival (25 - 27 August)
Leeds Festival (25 - 27 August)
Notting Hill Carnival (26 - 27 August)
Paralympic Games (29 August - 9 September)
Paralympic Games - Archery (30 August - 5 August)
Paralympic Games - Athletics (31 August - 9 September)
Paralympic Games - Boccia (2 - 8 September)
Paralympic Games - Cycling Road (5 - 8 September)
Paralympic Games - Cycling Track (30 August - 2 September)
Paralympic Games - Equestrian (30 August - 4 September)
Paralympic Games - Football Five-a-side (31 August - 8 September)
Paralympic Games - Football Seven-a-side (1 - 9 September)
Paralympic Games - Goalball (30 August - 7 September)
Paralympic Games - Judo (30 August - 1 September)
Paralympic Games - Opening Ceremony (29 August)
Paralympic Games - Powerlifting (30 August - 5 September)
Paralympic Games - Rowing (31 August - 2 September)
Paralympic Games - Sailing (1 August - 6 September)
Paralympic Games - Shooting (30 August - 6 September)
Paralympic Games - Sitting Volleyball (30 August - 8 September)
Paralympic Games - Swimming (30 August - 8 September)
Paralympic Games - Table Tennis (30 August - 8 September)
Paralympic Games - Wheelchair Baksetball (30 August - 8 September)
Paralympic Games - Wheelchair Fencing (4 - 8 September)
Paralympic Games - Wheelchair Rugby (5 - 9 September)
Paralympic Games - Wheelchair Tennis (1 - 8 September)
Paralympic Games - Closing Ceremony (9 September)

September

Bestival (6 - 9 September)
Carfest North (8 - 9 September)
Tour of Britain (9-16 September)
Southampton Boat Show (14 - 23 September)
Goodwood Revival (14 -16 September)
BUPA Great North Run (16 September)

October

Lloyds TSB Cardiff Half Marathon (14 September)
BUPA Great Birmingham Run (21 September)
Freeze Festival (26-27 October)
BUPA Great South Run (27-28 September)
Halloween (31 October)

November

Tar Barrels (5 November)
Bonfire Night (5 November)
London Christmas Lights - Oxford Street (5 November)
Manchester Christmas lights (9 November)
Remembrance Sunday (11 November)
Regent Street Christmas Lights switch on (13 November)
Cardiff Christmas Lights (15 November)
Cardiff Christmas Market (15 November - 23 December)
Birmingham's Frankfurt Christmas Market (15 November - 22 December)
Children In Need (16 November)
Belfast Christmas Lights (17 November)
Plymouth Christmas Lights (22 November)
Bath Christmas Market (22 November - 9 December)
Exeter Christmas Lights Switch On (23 November)
Edinburgh Christmas Lights Switch On (29 November)
St. Andrew's Day (30 November)

December

The Great Christmas Pudding Race (1 December)
Liverpool Santa Dash (2 December)
Trafalgar Square Tree Lighting Ceremony (6 December)
Christmas Day (25 December)
New Year's Eve (31 December)
Edinburgh's Hogmanay Celebrations (31 December)