Bon apres-midi from Le Tarn.
I'm on heavy clay too. Using the no-dig method quite successfully so just layering as much organic matter into the potager as i can lay my hands on. There's no quick fix to clay so i recommend adding organic material such as compost, worm castings, wood fire ash, coffee grounds, fumier (preferably not horse as they don't digest the weed seeds adequately), shredded garden waste and as many leaves as your can find time to gather. Leave the worms do what they're good at and don't rotovate to kill them off.
You can add gypsum to break up clay particles but i don't know what it's called here. Other than that just top the soil up in layers, don't dig it through and simply lift the weeds out easily as the odd one appears. I have very few appearing now that my levels are up about 30cms since November. Already in the ground: lettuce (4 varieties, beetroot, peas/mangetout (5 var), blette; rhubarb (3 var); strawberries (3 var); coriander ( 4 var) and tomatoes/chillis and peppers under polytunnel for another few weeks yet. Other seedlings hardening off prior to planting. All propagated from seed under grow lights.
I've had a fun time over winter and looking forward to a productive season. Wishing the same for everyone.