A drama dotted with laughs (or a comedy blotted with pain?) in which everyday problems are confronted, and avoided, over steaming cuppas and brimming glasses of white wine, Tender Loving Care explores friendship, family dynamics and England’s fraying social safety net. In other words, it’s a Mike Leigh film, and a lovely one at that. If it ends up being his last, as the 83-year-old writer-director has indicated, it’s a fitting and stealthily powerful way to go out — a low-key mic drop of sorts. The movie is warm and inviting, filled with giggles and gossip and gentle gallows humor; it’s also wrenching, with a topical urgency simmering just…