Pulling hair out s40 cuts out at idle

Hi, I bought an s40 year 2001 2 weeks ago!For 2 weeks I didn't have any problem with it till this weekend. I drove to Suffolk from Bristol and back 2 days later. That's quite a big distance but thought it can't be a problem to this car. Well on the way back in the last 20miles the engine cut out (at 70mph). The first moment of the first time I thought it was a really strong oncoming wind-that's how it felt( I'm a fairly new driver),but a second later realised the engine cut off. I rolled to the hard shoulder and couldn't restart it immediately, had to wait a couple of minutes then could restart! Drove 3 minutes and cut off again, than drove 10mins just to get home and cut off again... I have spoken to many people most of them say the fuel filter is probably blocked or on the tank cap there supposed to be a little whole that doesn't let any air in so there's a vacuum in the tank. Only one mechanic said something is wrong with the crankshaft! I don't want to get the car taken apart for no reason for huge amount of money... Can anyone help?