Thanks for the advice guys, i think i am going to see what the quotes for the rest of the work we are having done come back like before making a final decision.
I would look to do a lot of the work myself but the wife is expecting so it is a case of getting everything done ASAP and moving straight in to the finished article.
I will have to be content to add in some network cabling, bathroom speakers etc afterwards, although it does not help that the entrance to the loft is tiny there is what used to be a coal shed in the garage that i might look to be node zero (i just need to do some more research on whether it is advisable with the Newcastle winter weather).