1998 Other Vauxhall Models oil sump plug problems - rubber r

Hi

bad day yesterday with rover and my S reg Vauxhall Arena van

just an oil change, but a) sump plug had square inlet to take out, not a nut

borrowed a friends sump plug ratchet head

had to force it in as there is a bar under the sump that made it tight, then I coldn't get it back out!

or the plug screwed back in, was leaking a bt before, maybe bad thread, was about to change the washer but think I finished the thread off as I had to pull it back out with a tow rope after 1 hours hammering and pulling - hope didn't jolt anything else in the engine whilst whacking it

can't get it to screw back in, or a replacement

ordered sump head keys to try one more time but thought maybe a universal rubber replacement? Although can only trace them in the US, nothing online here in the UK.

hole is aroun 0.75inches

can't redrill larger hole due to bar under it and don't want to take the sump off with 20 oddd hard to reach bolts. Also van was  £500 so don't want to spend loads and don't have the money after rent and family!

thanks
Dan