Police patrols at airports and train stations and enhanced border checks have been in place since explosions hit the Belgian capital on Tuesday.
Two million Britons are expected to go abroad over the four-day weekend.
The government said there may be "some limited delays" and people should check travel advice before setting off.
Travel organisation Abta also urged holiday-makers to allow "adequate time" for extra security checks.
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Eurostar passengers have been told to allow one hour due to "enhanced security checks" with the cross-Channel operator expecting 22,000 people to use its trains to travel out of the UK on Good Friday.
London's airports will be busy with over 950,000 passengers set to depart from Heathrow, Gatwick, Stansted and Luton.
Meanwhile an estimated six million Britons are expected to make trips within the UK, with the RAC warning that the most congested stretches of road are likely to include the M5 south from Almondsbury, Gloucestershire, towards Exeter, the M6 north from the West Midlands towards Lancashire and all sections of the M25.
The motoring group claimed it was "inevitable" that popular road arteries will be congested and warned drivers to expect "heavy traffic and jams on major routes".
Rail passengers have been advised to check for alterations to their journey because a number of lines will be suspended as Network Rail carries out more than 450 individual improvement projects.
NR chief executive Mark Carne said he was "acutely conscious" that many people want to use the railway over Easter, but claimed it is a good time to carry out work on the network because there would be fewer passengers than normal over the four-day period.
Forecasters predict changeable weather over the weekend. Good Friday is expected to be mainly dry across the UK but a band of heavy rain is expected to move from west to east across the country on Saturday with the chance of some snow over the high ground in Scotland.
It will also be windy with severe gales in exposed areas and heavy thundery showers with hail possible. The largest rainfall totals on Saturday are expected over the north-west.
For those looking for a warmer holiday, Spain will be the most popular destination for an Easter break, with the Canary Islands in particular seeing large numbers of British holidaymakers, Abta said.
Holidays in Orlando, Dubai, Mexico and the Dominican Republic are also in demand.
Travellers on Easter getaways have been warned of possible delays because of increased security checks at transport hubs after the attacks in Brussels.