when you say the subframe is on the way out what do you mean, they are fairly substantial parts, is it rusted through? You can do this as a DIY job, just needs few decent tools sockets and spanners, axle stands. Sub frame is held on by about 6 m12 bolts under the firewall, 2 long bolts onto the chassis rails. The steering rack, rear gear box mount, anit roll bar, and wish bones are attached to it. They all unbolt, the only threaded thing on the frame I can remember is the rubber engine mount in the middle which is for the gear box mount.
Oh hang on I'm in the same town as you, G41 area, maybe you'd like to come my way and I'd give some advice if you like.