Hi and welcome to the gang
Snapped driver wiper arms is a growing problem. I've broken two of them myself and am now on my last one from my spares supply.
Assuming you've still got a broken stub left, you need a wiper puller OR a gear puller (the latter being quite common amongst DIY car people if you know any that will lend you one). As for the replacement, try the scrap yards in your area. The safrane is becoming an incredible rare beast to locate in them these days but sometimes you get lucky. My local is annoying me - he has his dads safrane and despite his dad dying years ago he is refusing to put the car into the actual breaking yard for me to pick to bits - he's keeping it outside the office taunting me instead lol.
No idea about the lag or VS wiper arms, you can but try I suppose and then let us know how you get on.
As for epoxy, it won't be strong enough to withstand the forces of the wiping I'm afraid. It will just snap off. You could in theory have it alloy welded though OR use something super strong like fibreglass wrapped / epoxied around it but not just epoxy by itself as it won't be strong enough. I couldn't comment on it being legal or an MOT failure but I can only assume it would be a bit dodgy.
Keep us updated as to how you get on and if you get chance, pics of your car would be nice (we always ask new members but very few bother lol)
One last thing, you're now out of moderation so you can post away
Saffles