Mate you're a guru.
I'm in the UK. I haven't bought the components yet, but I'm planning to get them in the coming month.
The Z87 was a good but insanely cheap mini itx mobo from MSI but I was going to pair it with either a i3 4160 or a i5 4460 (for the time being). I wasn't able to check the bios as I would've bought it from Amazon, and I was hoping I could update it by booting it up into bios.
Finding a Z87 motherboard that is compatible with Haswell refresh out of the box is somewhat difficult as Z87 was quickly discontinued in favor of Z97. The only Z87 motherboards that would support Haswell refresh without needing a BIOS update might be those from the last production batches or were returned to the manufacturer and updated before being resold. The most recent review on the amazon.co.uk page for the MSI Z87I AC dated May 2015 says "One little problem : out of the box the board did not want to restart, a bios update solved this and it has been running my G3258 Stable ever since at 4.4GHZ." The wording is a bit strange, but it seems to imply that the motherboard needed an update to support the G3258 properly. Looking here, we can see that the MSI Z87I-AC did not get G3258 support until BIOS version "7851v17". If you were going to use that with the i3 4160 it would not have worked, seeing as the same update that allowed the motherboard to recognize the G3258 also provided compatibility for the i3 4160. If the motherboard came with "7851v16" It might have worked with the i5 4460, but none of the reviews said what BIOS version the motherboard came with, so who knows what CPUs it supports. Potential headache there.
On the other hand, you don't need a Z87 or Z97 motherboard for a non-overclockable i3 or i5 processor. You can get a cheaper H81/B85 motherboard which are priced around £50 at the cheapest and it will work just as well as a Z87 or Z97 motherboard for most needs. The differences include the lack of enhanced overclocking support and certain features like SLI/crossfire support. I understand if you wanted to buy a Z87/Z97 motherboard to upgrade to an overclockable processor later on, in which case Z87 and Z97 would be preferable.
H81 and B85 motherboards are still in production and nowadays most of them come from the manufacturers' factory with recent updates that already support Haswell Refresh, unless you happen to buy a motherboard from a retailer who is selling old stock that has been left over from before Haswell Refresh support became more common. For example, this Amazon.co.uk listing for the Asus H81I-Plus mITX motherboard has a customer review dated from April 2015 which confirms that Amazon's latest motherboard stock comes with BIOS version 2105. If we look at the CPU support list for that motherboard we can see that 2105 is new enough to support both the i3 4160 and i5 4460, no problem.
If you don't mind posting your parts list, budget, and intended use, we could go over it to check compatibility and recommend changes for best cost and performance. For example: other than a cheap H81/B85 motherboard, you could buy that Z87 motherboard and pair it with the older i3 4130 (£90) or i5 4430 (£147) processors and then it would be compatible, no need to worry about needing a BIOS update to make the motherboard recognize those slightly older processors. You would just need to update the BIOS if you ever wanted to upgrade to a newer Haswell Refresh or Broadwell processor.
Edit: The Amazon.co.uk price for the MSI Z87I-AC is £90, were you going to buy that one at that price? CCL Online is selling the same model for £47. You may be able to contact CCL and ask them if they can verify what BIOS version the motherboard comes with.