FlyerTalk Evangelist
Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: BA Silver, TK E+, AA PP, Hyatt Globalist, Marriott LT Plat, Hilton Diamond
Posts: 13,041
Separate tickets means that IB has no obligation to get you to London. If their flight is cancelled, however, I'm sure that sending you on the BA plane will be their intention. But not until their own flight is cancelled... (if it happens)
There is so much fine print within insurance policies that it's hard to generalise about what insurance will cover. I dare say though that "essential travel only" does include returning home. Dis-inclination to connect via MAD probably isn't covered.
I would certainly consider buying another ticket MAD-LHR for Tuesday to avoid the overnight in a hotel. Or just get a hotel near the airport. To avoid the economy tanking completely, people in Spain are allowed to go to work, use public transport, etc. So I'm sure that taxi drivers will be out and about, trying to earn whatever money they can. Hotels will be able to feed you (but not restaurants), etc.