Two thirds of UK adults planning an overseas holiday or break intend to book online this year, according to research for Travel Weekly.

A survey of more than 2,000 adults by TNS in early February suggests up to 20 million could book their travel online, compared with more than eight million with a high street agent or by phone.

Researchers found that 42% of respondents (including those not planning an overseas holiday) said they would book online, 12% on the high street and 5% by phone.

Of course, booking online does not have to mean going direct or buying from someone outside the trade. Few high street retailers fail to sell online; Tui Travel reported 37% of its summer 2013 bookings were made online up to early February and expects this proportion to increase this year.

However, the results confirm consumers are increasingly at ease booking all kinds of holidays – including package holidays – on the internet.

Young adults are clearly most at ease: 55% of 16 to 34-year-olds said they would book a holiday or break online, against 25% of over‑55s. The proportion of student online-travel bookers (60%) was three times higher than those of retired age (20%).

More than half (54%) of adults in better-off households expected to book online, as did a similar proportion (52%) of those with children living at home.

Londoners and those in the southeast showed a similar propensity to book on the internet (54%), while less than one-third did so in Yorkshire, the East Midlands and Scotland and just 36% across the north – suggesting a digital divide.

However, the greatest variation in the survey results was in the proportion planning to take an overseas holiday, rather than how they would book it.

TNS found more than one third (36%) of respondents did not expect to go overseas in 2013 and a further 4% were undecided.

That suggests 60% intend to have a holiday abroad – a healthy market in light of previous research showing less than half the adult population (44%) are likely to go away in any year.

It is important to note people often express an intention to go abroad at this time of year but subsequently fail to do so – the young being especially prone to this.

February’s TNS survey found three-quarters of 16 to 24-year-olds planned an overseas holiday (and 56% intended to book online). Yet previous TNS research which asked 16 to 24-year-olds whether they had a holiday abroad in the past 12 months found 60% had not.

Almost half (48%) of adults over 55 said they were not planning an overseas holiday this year; neither were half the adults in less well-off households (47%).

Most adults with children did plan a holiday (68%), compared with 56% of those with no children. But the former appear more dependent on finding a cheap holiday – 38% of those with children identifying price as an important factor in whether they go away, against 28% of those without children.

TNS group director of travel Tom Costley noted “significant age variations” in online booking habits but said: “The proportion choosing to book via a high street agent does not vary to any significant extent, irrespective of age.”

He added: “It’s evident that being able to access a cheap price allows some to go on a holiday which might otherwise not be available to them.”