Newish hijet owner with a strange problem

Hello
Ive just recntly brought an daihatsu hijet 1.3 litre on an 53 plate pick up with a campervan plonked on the back. I brought it from far away 160 miles away and drove it back without any problems. Ive done a further 300 miles on top of that without any poroblems.

This weekend i went away init, drove about 130 miles there at a steady 55-60 mph as i was in no rush so that took me about 3 and a half hours. I had no problems what so ever. The temp guage goes up to half way and stays there sometimes it might just go over a bit half way.

Now the return journey. I was driveing back home and was doing about 70 mh this time. Drove 120 miles then the speedo just stoped woking? then about 5 miles after that i lost all power it was slowing right down untill it come to a stop on the hard shoulder but it was still running so i turn it of and i was like dam only got about 3 miles to the exit i need to come off and i havent got any aa cover all nowt. So i started it and fired up straight away and was back on my way with no other problems. Very strange

All i can think off is fuel. The fuel gage doesnt work but the fuel light comes on when low and when i started it up again on hard shoulder the fuel light come on for a bit then went back of but i had anuff fuel init. There was no hill when this happrnd just a straight run.

Does anyone know where the speedo cable is located?

Thanks

sorry its draged on but i want to give people much info as possible