Network cable questions

[Adam Funk]

Hi,

I need to put some more ethernet sockets in the house and I don't think
I can avoid running some of the cable parallel to mains wiring.

Of course I bought a roll of Cat 5e UTP cable last time, which seemed
good enough at the time.

I think I need to upgrade to some kind of shielded twisted pair if I
can't keep the network cable runs at least 200 mm away from the mains --
is that right? (I know crossing at 90° doesn't count.)

I'm also having trouble picking out the right thing from the RS
components website. When I put in "shielded network cable" it comes up
with Cat6a which is £474 + VAT for a 100 metre roll.

But if I look through the Cat5e there are more reasonably priced options
but I'm not sure what I need --- is F/UTP good enough? And do I need to
earth the foil shielding at either or both ends?

Thanks
Adam