L322 in tank fuel pump

Hi,
Had a problem starting the car a couple of days ago.
Drove car for 6 miles, no issues.
Left if fou an hour or so.
Got back in.
Car won't start. No warning lights.
Fuel gauge says half full.
No fuel at filter.
Put 10 litres in.
Fuel gauge says 3/4 full.
Car starts on 3rd attempt.
Go to fill up expecting bill for £120ish. Only took £50.
That makes me sure fuel gauge is right.
Car has been fine since.
I am wondering if the in tank ounp has failed. I have seen a thread on here that someone had a similar problem but I'm confused about what was said.
He said 1 side of the tank was empty and the other side was full.
Ok. That makes sense but, the empty side was where the in tank fuel pump sits. Surely if that pump failed the other side of the tank would be empty wouldn't it?
I would expect the inline pump to drain the passenger side of the tank if the in tank pump failed.
I'm worried about driving more than 140 miles now in case it just stops whilst moving.
My car is a 2003 L322 td6. Right hand drive UK car.
Thanks for any advice.

Have a look around section 19-1 explains fuel system

https://www.landroverweb.com/Pdf-files/Manuals/Workshop Manual L322 Range Rover.pdf

J

Mine would not pull fuel from "other" side of tank, replaced pump and then OK.
Fuel pump pulls fuel from tank and excess pressure siphons from other side.
If pump is starting to fail or the filter on the pump is dirty it will not siphon so fuel is only pulled from side with pump in.
I replaced just the pump inside the unit and all was ok from then on.