Buying a computer with no motherboard knowledge!

It's a decent motherboard if you're on a tight budget. However, it's a bad fit for the Core i5-2500k because it does not allow overclocking. You need to get a P67 or Z68 motherboard to overclock the CPU, and that will cost more. Or you can get a non-overclockable CPU and save some money; then the motherboard is okay.

Thanks for the quick reply!

Could you suggest a CPU that is cheaper but will still be decent or should I should keep the i5 2500k for future overclocking (not planning to do it at the minute).

Also I found this and it seems you can overclock? http://www.cclonline.com/product/87372/90-MIBH20-G0EAY0...

Well, there are various options. You could stick with the Gigabyte H61MA-D3V motherboard and get a Core i5-2380P which is only slightly slower:
http://www.ebuyer.com/342616-core-i5-2380p-64bit-mpu-3-...

Or you could get a different, but still cheap, motherboard and combine it with a processor from the newer Ivy Bridge generation, like the Core i5-3470 (which is actually a bit faster than the Core i5-2500k at stock clocks):
http://www.amazon.co.uk/dp/B0083U94CO/?tag=pcp0f-21

+

http://www.scan.co.uk/products/gigabyte-ga-b75m-d3v-int...

The other motherboard you found has a different CPU socket and is only compatible with certain AMD CPUs.