I really do not know - but I once had a taxi driver in London whom I am sure was trying to do this.

1) "Responsibility for the road network is primarily defined between trunk and non trunk routes. Trunk roads, which are the most important roads, are administered by the Highways Agency in England, Transport Scotland and Department of Economy and Transport in Wales. In England there are 6,500 miles (10,461 km) which account for 33% of all road travel and 50% of lorry travel, Scotland has 2,174 miles (3,499 km) (about 7% of the total roads in Scotland) accounting for 35% of all road journeys and over 50% of lorry movements and Wales has 1,000 miles (1,600 km). In London, Transport for London is responsible for all trunk roads and other major roads, which are part of the Transport for London Road Network. All other roads are the responsibility of the relevant local authorities, which is normally the County Council but can be a unitary authority. In Northern Ireland, the Roads Service Northern Ireland is responsible for all 5,592 miles (8,999 km) roads in the province." 2) "National speed limits on roads in the UK for Car/motorcycle, car derived vans and light goods vehicles up to 3.5 tonnes: Single carriageway: 60 mph; 97 km/h Dual carriageway: 70 mph; 110 km/h Motorway: 70 mph; 110 km/h" 3) Here a calculation: England: 10,461 km Let's assume this is 7% of the total *length* (like for Scotland: about the same proportion of total traffic) Total length: 149,443 km Scotland: 3,499 km (7% of the total length) Total length: 49,986 km Wales: 1,600 km Let's assume the same here: Total length: 22,857 km Northern Ireland: Total length: 8,999 km Total length for all: 231,285 km Let's assume that I am only mesuring the time to drive on those roads, not the time that I would need to go from the end of a road to the beginning of the next! That would probably make much more... Let's assume an average velocity of 97 km/h (this is a maximum! Probably not realistic...) I would need: 231,285 km / 97 km/h = 2384 h (a little less than 100 days, driving 24/7; or about a year, driving 8 h a day every day) And I suppose that after 100 km, I would get used to driving on the left side of the road...