Advise/ tips on mattress toppers.

I use a mattress topper and the mattress protector goes on over both mattress and topper. The bottom sheet is a John Lewis deep fitted sheet and fits easily. I might add that the mattress itself is unusually deep.

I’ve got mattress toppers on all my beds (not memory foam though as I don’t find it comfortable.)
I no longer use mattress protectors as the toppers are washable (although they are quite bulky).
Fitting of sheets depends a bit on the depth of the mattress and the quality of the sheets - better quality ones tend to be deeper - but when I buy new sheets I do make sure they are deeper.
Love my mattress toppers

Fitted sheets come in many different depths these days because of the variety of mattress depths. I don’t use a topper myself but would expect to put a mattress protector on top. Again it will depend on the depth of the sides of the topper.
Why oh why is it so complicated?

I have two toppers on my bed and use with a quilted protector and extra deep fitted sheets.

I use our memory foam topper without a protector, though I do put a protector over the topper on our guest bed.
We found we needed deeper sheets when we bought a new mattress, but there accommodate the topper easily.

You can get extra deep fitted sheets and mattress protectors. I’ve found mattress protectors are generally OK, but fitted sheets tend to rumple up.

We have toppers, with mattress protectors and so we buy deep fitted sheets from John Lewis. Nothing seems to move around whilst on the bed.

Measure total depth of topper plus mattress. The topper box might tell you it’s depth? In which case just add that to the depth of your mattress. That’ll save you de-boxing.
Go to Dunelm & there, you are likely to find fitted sheets of a depth to suit. If you’re not sure, look on the Dunelm website first.
My king size bed has a spare double duvet on top of the mattress. Finished off with the protector & fitted sheet. A much cheaper option than a topper & makes a wonderful “nest” for peaceful sleep.

Thank you all for your replies, I did not realise you could get different depths in fitted sheets.
Nonogran great idea I purchased topper from dunelm so should find right size sheets there.

I too get my toppers from Dunelm..Hotel make I think, very comfy. I don't use a protector with it. It costs £13 to launder the topper so maybe a thin protector is a good idea as it will fit in the w/machine. Deep fitted sheet.

Juicylucy, I recently bought a deep fitted sheet. I think it’s 28cm deep, from Dunelm. I’m away from home at present so can’t look. When I went to Dunelm I had to have a good look for it so if you can’t find what you need ask the Assistants to help. Sometimes the deeper sheets are hidden at the back or misplaced on the display so check labels carefully. Hope this helps.

As Blossoming says about sheets.

I have a very thick topper on the king size bed that won't go in the washing machine so there is a protector on it.

I bought last very deep fitted sheet from M&S. Perfect.

I have a mattress protector then a topper then a king-sized sheet. I'm in a small double bed (4') wide and had to buy bigger sheets once I'd got the topper. Well worth it though.