This week’s dramatic events on board United Airlines flight 3411 haven’t been a great advert for flying, but if you are travelling to somewhere like the south of France it’s the cheapest way of getting there … isn’t it?

It turns out that in terms of cost, the train can sometimes beat the plane – or at the very least give it a good run for its money.

A Guardian Money price test found that a family of four travelling at the height of this summer’s school holiday can get train tickets from London to Bordeaux and back for £428 all-in, which includes taxes and a decent baggage allowance. That’s less than easyJet once you factor in baggage fees. Meanwhile, taking a direct train from London to Avignon or Marseille in the south of France would come in at £476 return. (It’s perfectly possible that some people may be able to shave a little off these costs by playing around with dates.)

Or how about Barcelona? Our family of four would pay a reasonable £242 for return Eurostar tickets from London to Paris, from where they can pick up a train to Spain’s second-largest city, with fares starting at €59 (£50) per person each way for the 667-mile journey.

The low-cost airlines can’t be beaten on price out of season, or if you are completely flexible with dates. But if you are restricted to the school holidays and have a particular European destination in mind, once you multiply the cost of the flights by four and add in taxes, baggage fees, getting to the airport etc, you can quite easily be looking at £600-£1,000.

The train is clearly only a realistic option for certain destinations, but if you live in or near London and are planning a trip to the south of France, northern Spain, Italy or Germany, you might be pleasantly surprised by the fares.

Next month marks two years since Eurostar launched its direct service to Lyon, Avignon and Marseille. And a new service to Bordeaux in southwestern France – named number one in Lonely Planet’s list of the top 10 cities to visit in 2017 – launches on 2 July. The journey, which involves a change of trains in Lille or Paris, will take five-and-a-bit hours thanks to a new high-speed line in France which lops off more than an hour. Fares from London to Avignon/Marseille start at £99 return, and for the new route at £110 return.

But it’s not all about price. The endless rules and security checks have made flying a soul-sapping experience for many – and then there is the environmental impact. “Train travel is a more rewarding, low-stress alternative, which brings us closer to the countries we visit and reduces our contribution to climate change,” says Mark Smith, who runs website The Man in Seat Sixty-One (seat61.com), a treasure trove of information on rail travel in Europe and further afield. He adds that the top destination pages on his website are, in order, Italy, Amsterdam, France and Spain.

Our price test was based on two adults and two kids, aged 10 and eight, departing on 3 August and returning on 17 August. For return tickets to Bordeaux, Eurostar would charge £428 (the adult fares were £55 each way, and the child fares £52).

The train we picked leaves London St Pancras International at 8.04am and arrives at 3.52pm, while the return leaves at 12.08pm and arrives at 7.03pm. There was quite a lot of availability for the £55 fares during July and August. Smith says it’s easier to change in Lille than Paris.

For the same family on the same dates, opting for the cheapest Gatwick-Bordeaux flights, easyJet would charge £455, which includes £70 for two hold bags weighing 20kg each, but no other extras. However, Ryanair (London Stansted) would come in cheaper: £307, which includes £78 for the bags.

When we looked at direct trains from London to Avignon, which takes five hours and 50 minutes, Eurostar would charge £476, made up of four £70 adult single fares and four £49 child fares (or £462 with a change in Lille or Paris). Marseille, which takes six-and-a-half hours, also came in at £476. For flights to Marseille, easyJet (Gatwick) would charge £474, while Ryanair (Stansted) would want £317. Both these prices include £78 for the bags.

Kids under four travel for free on Eurostar provided they sit on a grown-up’s lap, and each adult can take two pieces of luggage, as well as a small piece of hand luggage, with no weight limits. Pushchairs and prams are free.

So where else can you get to by train for not much money? Smith says Paris-Gare de Lyon to Barcelona Sants, which takes 6 hours 25 minutes on double-decker high-speed trains, is a “lovely” journey, taking in pretty French villages, flocks of flamingos and great views of the Pyrenees. Fares start at €59 (they do exist, we checked) and Smith says one of the cheapest places to buy is Trainline (formerly Captain Train), at trainline.eu.

There’s also the Paris to Venice night train run by Thello, which starts at €35 one-way in a six-berth couchette, €55 in a four-berth, or €95 in a two-bed sleeper.

Deutsche Bahn is offering fares from London to Germany from €59. After travelling from London to Brussels on Eurostar, you continue on an ICE high-speed train.

Meanwhile, it’s possible to go from Brussels to Prague for as little as €20. “You don’t get much control over the trains or route, it involves three or four changes and takes a day, … but it’s true,” says Smith. Book via the Czech Railways website). Smith’s own website tells you what you need to do.