Britain's drivers are being warned to expect a 'Frantic Friday' as millions hit the roads tomorrow for what could be the busiest August bank holiday weekend on record.Some 20million car journeys will take place from tomorrow to Monday as families attempt to make the most of the last bank holiday before Christmas.The RAC said this total was the highest number since it started analysing summer bank holiday travel plans in 2015, warning tomorrow is 'likely to be mired in traffic'.The motoring organisation predicted 4.1million getaways on tomorrow, followed by 3.8million on Saturday, 3.1million on Sunday and 3.4million on bank holiday Monday.A further 5.5million journeys will be spread across the four-day period, with many motorists unsure which day they will hit the road until nearer the time.As day-trippers compete for space on the roads with people going on short breaks, transport analytics firm Inrix identified a number of likely congestion hotspots:M25 anticlockwise from Junction 17 in Hertfordshire to Junction 12 in Surrey, which could see delays of up to 50 minutes around midday tomorrow;M25 clockwise from Junction 15 in Buckinghamshire to Junction 19 in Hertfordshire, where delays of nearly an hour are expected tomorrow night;M1 south from Junction 16 in Northamptonshire to Junction 6 in Hertfordshire, which could be blighted by delays of up to 70 minutes at around 3pm on Sunday;M5 south from Junction 15 near Bristol to Junction 23 in Somerset, where delays of up to 75 minutes are predicted at noon tomorrow as people head to the coast;M5 north from Junction 11 in Gloucestershire to Junction 1 in the West Midlands on Monday at around 7pm on Monday, where motorists face 45-minute delays;M5 North from junction 25 for Taunton to junction 15 for the M4 Almondsbury interchange, where delays of 45 minutes are expected at 3.30pm on Monday.The impact on oil prices from the conflict in the Middle East means filling a typical 55-litre family car with petrol costs about £89 compared with £74 a year ago.