The internet is full of garden resources if you know where to look, and many people will use sites for advice as well as purchases. You may have a number of gardening books but there is always something cropping up that you will need advice about. Plants shrivel, leaves develop holes or tomatoes fall over with wilt. You see insects you have never seen before (little green shiny flies on camellias in the sun are harmless). It’s easy enough to check up on diseases – try the BBC site gardening pages for a start.
If you want to track down a particular plant and find out about it try the Royal Horticultural Society (RHS) site. It is often essential even when you’ve bought a plant to find out how to care for it in the longer term.
My garden is at a highish elevation and pretty exposed and I expect to lose up to one in five plants every year (some perennials aren’t so long lasting anyway). Some years I may lose a third to a bad winter. This does mean that I need to replenish every year. I’m going to get a couple of species of wormwood (southernwood just like in my grannie’s garden) from the Cottage Gardens website and I’m going to try another fig tree from Bigplant nursery but this time I’ll keep it indoors over winter.
Most vegetable seeds I do plant myself but I will buy my seed potatoes from Thomas and Morgan’s website and get a load of new garden netting etc supplies from the wonderful National Vegetable Society Website (NVS) or tools from LBS Garden Warehouse. A major advantage of these suppliers is being able to choose from such a wide range of products and take time over it.