Spots can come on with main beam, either with the std kit (and enabling) or by the traditional method of relays from the existing main beam. But best to be able to stop them from coming on if you need to via the switch.

You could put the switch (or use a different switch) somewhere else so you don't cut into the dash area. Bodsys Brake Bible
Software Updates Contact me
RRS Timed Heat/Remote kits - Contact me
BAS Engine Re-maps/ EGR Blank EuIII and EuIV
Clock On The Dash/ SNOTM /3Flash / BT Update /Service Reset/Error Codes read\ Gearbox Reset
See it HERE

I can enable them with my IID Tool I think. It's the rest of it that looks a bit daunting. Just had a read of some earlier threads - someone mentioned it being a pig of a 6 hour job to install them! That's a pricey proposition (or a fair chunk of a weekend on the driveway).

I might ask a local indie that I'm going to use for servicing from now how much they would charge to do it. That's assuming they've ever done one before, of course. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

You should be able to do it with IID. If not, then gap will update it for that function I'm pretty sure.

These are a bit of a pig, but mostly just time consuming. Make sure the cuts are accurate etc. any reasonable auto electrician should be able to do it.  Bodsys Brake Bible
Software Updates Contact me
RRS Timed Heat/Remote kits - Contact me
BAS Engine Re-maps/ EGR Blank EuIII and EuIV
Clock On The Dash/ SNOTM /3Flash / BT Update /Service Reset/Error Codes read\ Gearbox Reset
See it HERE