Anyone fancy helping me out with a bit (lot) of welding???

Hi, A couple of ideas that.might improve your chances :
Offer to do the striping and cutting out the problem areas for anyone who offers to do the welding (makes the welding easier)
ask on the normally helpful mig-welding-uk forum (unlikely but you might get lucky)
Barter? If you can't afford to pay a lot, can you trade some of your time or skills ?

Hope you get sorted   

The trouble is, welding is one of those arts that many say they can do, but few can actually do well. It's dirty work, and when welding up rusty cars it's quite tough going sometimes. Without doing it yourself, you are going to struggle getting it done cheap to a good standard I'm afraid. Speaking for myself, if someone I was mates with locally asked me to throw a day at it for them I would, so long as they helped out and paid for the parts and consumables, but I would expect a favour back from them at some point. But if they asked me to do a whole car the answer would almost certainly be "Sorry mate"...

Your biggest issue is the unseen. You have no idea how bad it is, or where the rot goes. From personal experience it is so often an iceberg thing, you only see the tip. Typically cars rot from the inside out, and that is the worst kind of rot.

The way, the only way, you are going to get it done at a reasonable rate to a reasonable standard, is to strip the car right down, get rid of everything so you have a bare shell (I would recommend this before doing any sort of resto work anyway). Then, you want to (as suggested already) put to it with the grinder, and cut out every single shred of rot you can find. At this point I would then say "Go get it shot blasted" but no one ever does because that then means paint etc (which, ironically, is what welding usually means too!).

Then I would get someone to come and cast an eye over it. I would feel WAY better laying seams down on a car that has already had the rot carefully cut out and has the correct panels ready to go, with someone there to do the clean, prep and grinding (the dirty work). Doing that will also give you more insight to how many hours go into welding up cars, and what a big ask it is for someone to do it cheaps / free.

Indeed. You don't want someone to do what is essentially a patch job only to find it rots out again in a couple of years.
I'm also careful about what favours I do for people too. I wouldn't fancy a repeat of the time I fixed someone's wiring when they broke down (snagged and melted live feed to coil, so took a live feed from the electric fuel pump to get them home) and explicitly warned them they urgently needed a rewire asap and it was in dangerous condition... only to find a few months later they were on a forum blaming me for "bodging" their ignition circuit which "caused" an electrical fire in their dashboard. Nowt to do with the 40 year old wiring, corroded earths, rats nest of under rated cables, burnt insulation, unfused switchgear, twist & tape electrical connections, aftermarket unfused fag lighters running heated seat pads and usb ports, and fuses replaced with bits of single strand copper mains cable then..? Grrr...