[quote="DIY Disaster"]My boiler and header tank for the central heating / hot water are in a cupboard in the spare room taking up a lot of space is it possible to move this up in to a very large loft?"
Yes. Whether it is practical or not in your case cannot be determined on a site unseen basis.
"how much would this project cost if I had a professional to do it?"
The length of a piece of string is twice that from the middle to one end.
Recommend you get a plumber in to quote you properly for the job. Then get two more for comparison purposes. Then you can decide how to proceed.