Meh, the fuel pressure is low enough that you can easily cut the bad bits off(behind the left rear wheel usually) and replace them with a rubber hose and some clamps, you can even flare the end slightly if you're worried. I've done tens of thousands miles like this with no issues whatsoever. If you get to replacing the fuel filter to tank because you cracked the line while replacing the fuel filter, use this as an opportunity to replace the Jag fuel filter with a similar size one with push fittings like on the XJS, much easier to replace afterwards, the X300 design is absolute garbage. I've cracked quite of these fuel lines next to the filter while trying to replace it and its almost impossible to remove the main line to fuel filter line without snapping it unless the filter was changed regularly every couple years from new. At this point I think the safest way to remove the filter is to cut the main line just behind the nut. You can then hold the fuel filter to fuel tank nut with a large adjustable spanner against the car body and put a socket over the other end of the filter that you just freed up by cutting the other end and then using a few extensions and a breakers bar turn the filter out of the nut that you're holding with the spanner at the other end. I've replaced a few of these filters now and each came out twisted like pretzel before I was able to undo it from that nut, even with a large breakers bar.
With the fuel filter out and on the bench you should be able to hold it in a vice and undo the cut end and save the nut. You will only loose about a cm of the pipe and can reflare the end before replacing filter. Any attempt at turning the nuts will almost always end up in twisted and broken lines.

 

Good idea regarding the pre filter pipe. I was hoping to change the filter, which is how I screwed up the post filter pipe. I'll see what access there is and have a go at it.

 

The new filter should have 2 / O - rings total recessed inside the filter body ends , 1 each side

Hard to see