don't bother
move to a studio which is sound proofed already with air con
don't **** about doing it yourself, it'll cost you , take ages, won't really work without serious structural work and totally piss you off.
take it from me
i did it.
no put your efforts into finding a pre built studio space ( there most be one in leeds there's hundreds in london) whith all the trimmings
it may cost you a little more but if you weight up the costs you'll probably find it cheaper in the long run.

(i reckon anyway)

but that is coming from a MISERABLE CUNT !!!!!!!!!
as you called me on friday which by the way i recorded and will play back to you for the next few years to come.

if you are going to do it though
go to the library and get a book on home studio design you'll be surprised at how helpful it'll be rather than listening to miserable cunts on the internet