We left beds, wardrobes (some built-in), sofas, coffee table and some shelves, curtains, white goods in kitchen (including cooker, washing machine, fridge/freezer, separate freezer, dishwasher and tumble drier), dining table and chairs, saucepans, lawnmower and gardening tools.
Electrical appliances require a check by an approved electrician and there should be an annual Gas Safety inspection. All fabric and upholstery supplied by landlord, including mattresses, has to comply with a recent fire retardancy standard or be pre-1950.
We left mattress protectors but not linen. Think most people would prefer to use their own unless you are doing holiday type lets and then they'd need to be laundered after each one. Could you buy some vacuum bags and store yours in the loft, or pay for a small self storage unit.