A free information service from spareroom.co.uk
Obviously the main thing you're providing is the room itself - usually if you're taking in a lodger you'll offer the room furnished. If you're operating under the 'Rent a Room' scheme you must offer the room furnished. In addition the lodger should expect to be allowed use of communal areas such as the kitchen, bathroom and any living spaces. As often as not these days lodgers share the accommodation with you as if you were both renting a flat together, it's just that it's your flat. That means you can realistically expect your lodger to do their share of cleaning and take care of their own laundry and cooking. Of course, if you get on well with your lodger, you may well end up cooking for each other without it being any kind of formalised agreement but you shouldn't be expected to feed your lodger.
You should, however, discuss what you expect from a loger before they move in in terms of cleaning, laundry and so on. If someone expects you to do all the cleaning they'll be in for a shock when you don't agree. Generally speaking these days it's common to expect a lodger to do their own cooking, cleaning and laundry but it's better to discuss it in advance so there's no confusion.
You can provide linen and towels but, equally, you can expect your lodger to bring their own. Additional services often traditionally associated with lodgers such as laundry and providing meals are not necessarily the norm these days. You can provide these services and charge extra for them if you wish to but you won't be expected to in many cases. If you do charge extra for meals and other services you'll need to take this into account when you calculate your income for tax purposes. The limit of £4,250 you can earn tax free includes all income so, even if the rent is less than this but the extras take it over the limit, you'll have to declare it.