Cross Member?? lol!

Anyway! I have a rusty crossmember, possibly an MOT failure but what do you guys think? See pics attached.

I am going to attempt to weld some patches on myself as can't afford to replace it. £500!!

Does anyone know what guage of steel to use? I am going to use an arc welder, as that is all I have ever used so I kind of know what I am doing with that.

Any advice'd be great. Thanks.

put a grinder to it first and see if you have any meat to weld onto before you go out and get a whole lot of 2mm steel to plate it... I think britpart do a cheapish replacement crossmember, if u do use the britpart one though be sure to seal it with 3m stonechip or even better raptor underseal as they would appear to be made out of recycled coke tins.
good luck.