Posted: 04/12/2016 at 18:17
Your citrus photos show the plant close to a radiator - citrus abhor a hot dry atmosphere hence they don't make good "house plants". If your radiator is working, I'd suggest you keep the plant a safe distance from it.
Keep it in your sun lounge - at this time of year, it won't mind a bit of cold. Much better there than in a heated room in your house.
The chlorosis will occur if you don't keep the plant fed properly - specialist citrus feeds are perhaps better than Baby Bio but it won't kill your plant. Citrus will also drop some leaves throughout the year like any other plant.
4 Sasons is a good old variety..........unfortunately the UK climate is not ideal for ripening the fruit .