175k Krisflyer (236,250 Velocity) MEL-SIN-MXP/FCO in business class with Singapore Airlines.
278k Velocity for the same route above redeemed with Virgin Australia and with less availability than Krisflyer has (generally).
Milan is closer to Lake Garda.
I don’t believe the 2 airlines have good free/cheap stopovers within EU so I would recommend finding you own separate way around EU once you are there. If that is the case, you could structure your main flights to fly into LHR, Munich, etc. depending on where you plan to visit and how your itinerary goes.
Best to fly into one city and out of another to avoid having to double back. Doesn’t cost more points to book 2 one-ways. Avoid flying internationally out of UK to avoid having to pay APD.