J.O.
Before you start this job download the workshop manual from the manual section at the top here. Then read the section on lower crankcase removal (=sump removal).
You must remove the "T shaped cross"(=prongeron) to get at the sump.
You must also remove a bit of the exhaust system.
I had to do it earlier this year as I cracked my sump at the Ypres meeting

. I found it easier than I expected.
Once jacked up, put axle stands under both jacking points under the "A" posts. Remove wheels and support the suspension with 2 more axle stands, but do not raise the suspension: just support it. Once these are in place DO NOT MOVE THEM until the job is finished.
Undo prongeron bolts one by one then remove prongeron. This turned out to be quite easy as all my bolts were reasonably free and not rusted.
Remove the front part of the exhaust after the cat box. If rusted use heat on the studs and nuts. You may need to buy new ones: readily available.
You can now undo all the sump bolts and remove the sump. Do your repair. Clean all old sealant off sump/engine block, then replace sump with new sealant. There is no gasket (jointe).
Whilst the sump and prongeron are removed, change the oil filter: access is very easy!
Replace exhaust then replace prongeron after giving it a good clean and perhaps a respray!
Bit simplified but job is quite straightforward if you have some mechanical experience.
Good luck and don't be afraid to ask questions

Fredjohn
La vie passe vite: vivez la avec élan.
Elan SE turbo 1992
Emira 2023
Mercedes Benz C200 estate
Lotus Evija Danish edition