I buy knickers at M&S when back in the UK for ds, dh and myself. They are also good for tights and knee highs for under jeans and I have lots of their long sleeve T shirts, some of which I have had for about 6 years, and they are still fine. Their socks are good as well.
The £9.50 jeans for men are fab for ds, as he is growing like a weed, so it doesn't hurt to replace them when he has a growth spurt, and I love their moleskins for men; dh has several pairs and they last for years. I also buy the blue harbour polo shirts for ds, as he is hard on clothes and there is no point buying crew or fatface, just for him to rip clothes to shreds. Dh has some as well from circa 2007, and they are still fine.
I quite like some of their shoes as well, as it is hard for me to get 3.5s and they do them. Their shoes can be quite wide as well, which is good for me.
I bought a couple of linen tops there for the summer last year, and am wearing them again this year,as they have lasted well.
Dh is now back in suits for work, as opposed to uniform atm, and we bought a couple of suits for him, which weren't too expensive, and the quality is OK.
I like their cookbooks, the prosecco is good, as is the quality of the fruit and veg, and the price (compared to Belgium) is so reasonable. Their cooking utensils are great as well, and I am hard on things like that.
As I am abroad I tend to buy most of my clothes from Lands End, plus I have a wardrobe full anyway, so just restock with jeans and fleeces when I need them.