Well it's done!
Decided that a bridge wasn't going to cut it so I went the whole hog.
First I dropped the subframe for access
Then I drilled it with an 18mm drill to enlarge the hole
Next I got an m20x1.5 tap and re threaded the hole (took a bit of time as I should have used an 18.5mm drill but who has one of those!)
Finished off with a new sump plug and washer.
Filled up with oil and off we go! (May drain the oil again in the future to make sure no filings but did run a fair bit through before anyway)
Job done, total time hours and hours!!!
Be careful with those sump plugs lads
and the gloves helped....
Job well done! Unfortunately mine was split so I couldn't do such a superb repair