Dedicated electrical line - UK

I would doubt there are any / many differences in recommendations between the US and UK, although the voltage is different. You would want a dedicated line for your amp(s) and one for the remaining audio components. Use oversized wire… 10 gauge and audiophile outlets. Special audiophile grade wire for running dedicated lines is available… I am sure this would be a little bit better… but this could start getting costly. Here the value now and in the future of your system should be taken into account.

I don’t think it is as important, but since you are doing all. The same for your AV system.

Thanks @ghdprentice - the only reason for the Uk comments was if anyone was posting links to wire or other bits. 

I have 2 rooms being replaced and 3rd room adding. 

can’t wait. 

You will be in for a real treat. Each time I have done it I have been happily surprised and never heard of anyone who has not.