Pluming in new radiator in extension

Hi,

I am in the process of installing some pipework for a vertical radiator in a extension.

I have three options available really to routing the pipes and just wondered the best approach.

I am leaning toward No. 3 below as it means the joints can be accessed later if required.

I have channeled them into a solid wall which will be plasterboard on top using dot and dab.

The floor is probably going to be a floating floor (chipboard on celotex).

I am using Copper Pipe.

1. Bring pipes directly out wall into radiator using an angled Trv - small risk here is if pipe is ever cut too short after it's been plastered then I am stuck
2. Bring pipes out wall below radiator and bend or use elbow to go up to the radiator - ok but not sure how I could cover the elbow as I planned on using rad snaps to make them look chrome or possibly white, other option is to paint them but less preferred.
3. Bring pipes down in the wall below the floor (which goes a bit below DPC) and then up through the floor vertically into the radiator. This means most joints could be accessible under the floor for possible future leaks! Slightly more awkward to do piping but sounds ok - DPC will be tucked behind the pipes and lapped into the original house DPC, just need to make sure I don't melt it with a blow torch!

Oh and pipes are coming down from the loft (its a bungalow), and I also have installed a isolating valve in the loft to make life easier.

Is a drain cock needed here? its only 1 rad and not much pipe. Seems a bit overkill but could be useful although I have very limited space for it.

Any suggestions would be good.

Cheers!