940 crankshaft main oil seal

[Jfxv]

Hey guys,
First post here, figured I'd introduce myself first. I'm Jake, studying engineering at uni, and bought my first Volvo in May - 1997 945 Classic (2.3 LPT), had about 150k on the clock. It's still stock, but I have plans for it to be a fast daily once my insurance as a 20 yo comes down a bit.

It's had a few issues since I bought it, replaced the clutch and a load of hoses, cleaned out the PCV system after noticing I was burning oil, and a general small things associated with age which are on the list of things to do. Until today, it ran pretty nicely aside from a slight misfire and lumpy idle, and was great fun to drive - sideways is the right way, right?
symptoms
Today, after a couple of short trips just driving around town, noticed that there was a fresh, suspiciously oily-looking puddle in the sump guard tray. I couldn't get the tray off as I've got barely any tools with me at uni, and no axle stands (just ordered some though). Got some pictures though and the source is somewhere around the bottom of the cambelt cover / crankcase, leading me and my more mechanically intelligent friend to believe that it's a leaking crankcase front main seal. First off, does this make sense? I'll hopefully upload the pictures I took in a second. The last couple are from underneath the cambelt cover - you can see the auxiliary belts in the picture.
I also noticed that during and after stationary revving, there was a fair amount of white smoke which smelled oily coming out of the back again, after I thought that had gone away since cleaning the PCV system. Not sure if it's related - I didn't think it would be if it's the crankshaft seal. It didn't seem to be cold enough outside for it to be the usual condensation in cold weather, I'm in Exeter and it was around 8 degrees today.
solutions
Second, how hard a job is this to sort out? Internet says it's a big job, most likely requiring removal of the engine (should be alright, my dad has an engine hoist and plenty of tools), but has anyone does this in the past / can you advise? Any pitfalls to watch out for?
I was tempted to just try to engine swap it if it's too much of a big job, I do like the B230FK / M90 combo but at the end of the day, it is a 4 pot and it doesn't sound amazing. Any recommendations for swaps - if the repair job is too much hassle of course?
Cheers!
J