The inspirational second world war veteran Captain Tom Moore has been appointed an honorary colonel to mark his 100th birthday on Thursday in recognition of his efforts that have raised nearly £30m for the NHS.

The centenarian will become the figurehead for the Army Foundation College in Harrogate, which trains 16- and 17-year-olds, on a birthday that will be celebrated with more than a hundred thousand birthday cards – and two special flypasts.

Two helicopters are due to fly over Moore’s home in Bedfordshire in the afternoon, while the flight of a wartime Spitfire and a Hurricane will be broadcast live on BBC at 8.20am, to avoid large numbers of people trying to travel and see it.

The veteran said it was “quite extraordinary” that he was turning 100. “It is even more extraordinary that I am doing so with this many well-wishers and I am in awe at the response my walking has had”.

Some of the 125,000 100th birthday cards sent to Colonel Tom Moore are arranged at Bedford School in advance of his birthday on Thursday. Photograph: Shaun Botterill/Getty Images

Well-wishers have also sent him more than 125,000 cards, which are being stored at his grandson’s secondary school ahead of delivery – and he is also due to receive a personalised message from the Queen.

The events cap a heady period in which Moore first captured the nation’s imagination by raising millions by meeting a promise to walk the length of his 25m garden 100 times before his birthday to raise money for NHS charities.

The veteran originally set out to raise £1,000 but donations wildly exceeded that, and he completed his efforts in the middle of the month, surrounded by a guard of honour. At that point he had raised £12m, but it has continued to rise and passed £20m on 17 April.

He went on to record a cover of You’ll Never Walk Alone with Michael Ball, which went straight to No 1, making him the oldest artist to have a chart-topping record in the UK.

The Royal Mail said it would paint a mailbox near his home NHS blue and the postal service has already been stamping all mail with a special postmark to celebrate the veteran’s 100th birthday.

Soldiers from 1st Battalion The Yorkshire Regiment provide a guard of honour as Captain Tom completed his 100th length of his back garden on 16 April. Photograph: Ministry Of Defence/Reuters

Moore was also presented with another second world war Defence Medal, replacing one that he had previously lost, ready in time for next week’s VE Day celebrations. Born in 1920, he trained as a civil engineer before serving in India and Burma.

Ben Wallace, the defence secretary, said: “Captain Tom is simply inspirational and I am absolutely delighted the army has honoured him in such a fitting manner. He not only embodies the spirit of our incredible veteran community, but the resolve of this nation.”