Rust removal, (welding?) And underseal north west

Hi all,

Inspired by cheshirecat's post about losing the leggy to rust, I've already had welding on my skills underneath, looking underneath I can see some rust and I know there's rust showing on my mot
"Monitor and repair if necessary (advisories):
Vehicle structure is corroded but structural rigidity is not significantly reduced (6.1.1 (c) (i)"

I want my car perfect underneath, then undersealed - where do I go??
I live in bury, north Manchester

Any help much appreciated
Alex

Ps - obviously doesn't have to be in bury! But not....Penzance :D