The view through the windows of the packed 11.55 London Paddington to Penzance train was of burst rivers and drowned fields.

Those on board were the lucky ones. On Friday, the train was the first to make it through to the west country for days after torrential rain plunged large parts of the UK into chaos. Rising water levels threatened to swallow the track as passengers grew increasingly bewildered.

"We were told one thing at Paddington," said Chris McColm, 70, who was trying to get to Totnes in Devon with her husband Tony. "I looked on the internet and it was so confusing. I called up and it was useless. The man on the phone just couldn't answer me. On TV, they said no trains from Paddington. But when we arrived we were told a train had left. We've just gone backwards and forwards – is the station open? Are the trains running? Things happen, you can't always run on time, but all I wanted was a straight answer."

Respite from the wet weather is some way off. Weather forecaster MeteoGroup warned that the entire country was set to be drenched by persistent rain sweeping in from the Atlantic in the days ahead.

According to the Environment Agency, places at risk include all of Wales, Herefordshire, Cornwall, Devon, Somerset, Dorset, Hampshire, Sussex, North Yorkshire, Lancashire, Oxfordshire, Gloucestershire, Shropshire, Hertfordshire and Buckinghamshire. Some 570 properties have been flooded since 19 December, while more than 110,000 warnings have been issued to people in homes at risk of flooding.

The Met Office says that just 46mm (1.8in) of rain needs to fall before the month is out for 2012 to be the UK's wettest. That appears to be a foregone conclusion. A drenched, waterlogged Britain is heading for a sodden beginning to 2013. The south-west has become a watery realm apart, as the populations of Devon and Cornwall struggle to leave to visit relatives elsewhere.

Niall Underwood, 20, left his Brighton home on Thursday to visit his grandparents in Looe. "Although I set off yesterday afternoon, I had to break my journey in London last night," he said. "It didn't ruin my life but it's frustrating."

Other passengers on the 11.55 had tales of greater hardship. On the Sunday before Christmas, Freda Donovan, 67, left St Austell to visit Lytham in Lancashire. The 07.20 was cancelled so she took the 07.50 to Plymouth where a rail replacement service had been laid on. "There were no buses, it was chaos. I waited about two hours for a bus, which took me to Taunton and then the train to Birmingham, then to Preston, then to Lytham. I was three hours later than scheduled. There were people in tears."

A 74-year-old woman who declined to give her name recalled her trip to visit family in Epsom shortly before Christmas. "I got the 06.40 to Exeter but was sent home from Plymouth," she said. "It was such a dramatic moment. Hordes of people were all told to go home and so I did. We had to wade through water."

Gazing on to submerged moorland around the Somerset Levels, a fireman from Axminster said the floods were the worst he had known in years. "We've had all sorts. Houses flooded. It's really bad. New roads have been ripped up, pot holed again. There are diversions everywhere. Drivers are confused because of road closures."

On the final stretch to Plymouth, where the line hugged the coast, the train's windows started leaking. Flood water swirled close to the tracks.

"It's not fun for anyone – staff, customers – but it was exceptionally bad this year, what with the floods and landslides," said the train's driver, who gave his name as John. "Exeter was the worst – it's low-lying so it was all flooded and in Teignmouth landslides had fallen on to the track. There was sheer disruption for everyone. Something needs to be done. We need to invest in infrastructure."

A station guard agreed. "Newton Abbott has taken the brunt of it. Exeter has been the busiest. The line was washed away at Cowley Bridge. Eight or nine years ago, it was almost as bad – but it didn't last this long. This time, it just got worse when the line reopened and then the rain started again. They could divert the water from that area. It'll cost a lot of money, though."

The rain has made the drenched inhabitants of Devon and Cornwall acutely aware of the region's vulnerability to the elements. In the centre of Plymouth, locals in the near empty Eagle pub said the weather had left them feeling isolated. "It's been absolutely soaking here – and there's more to come," said Anthony John Thomas, 56. "Everything was washed away again at Dawlish; Victoria park in the city centre got flooded; Gdynia Way has flooded repeatedly; the main road in from Plympton was blocked – it's been chaos."

He took a consoling sip of lager. "The roads and drainage are really poor. Plymouth is tricky to reach, you either go through a creek or over a creek, it's all bridges and valleys. To get here you have to go down one of these routes and the routes keep breaking down. It's just so cut off, it's the backwater of Britain."