If a Trillion Pounds were the GDP of a country, it would qualify as the 13th richest nation (just behind India).
Its almost 12,000 times the number of £1 coins currently in circulation.
If there were enough £1 coins available; you'd need a colossal 10 million tonnes of them. Which is the approximate weight of 32 of the World's largest Supertankers.
Or you might attempt 385,000 Great Train Robberies? Although Acapulco might get a little crowded afterwards.
How about if on the day that Queen Victoria died you dragged £25 million Pounds in used notes off into the woods and burnt them; and then repeated the exercise EVERY day since? You'd still be two years short of destroying a Trillion Pounds.
Assuming the Government were able to pay back the Debt at a rate of £20 Billion a year, it wouldn't be repaid until the year 2060 (not including the huge interest payments meantime).
Alternatively, you could close every school in the UK, sack all the teachers and maybe pay it back in less than 30 years.
Its 5 times the entire economy of Hong Kong.
Its 30 times the size of our Defence budget or approximately equal to the USA's massive defence spending.
If it were turned into £20 notes you'd need 2000 Securicor vans to move it.
UPDATE: £1T debt? More like £4.1T