I've currently got a lodger, and have had several previously (and before that I house-shared, which I never hated).
Firstly, big fat NO to sharing meals. I can guarantee that you will have different tastes, skill levels, budgets and dinner times to the lodger. It's a recipe for disaster (pun intended). Each cook your own meals. I make it a rule that the lodger has to provide anything of theirs that needs washing up after each use (pans, cutlery etc) but we share other things (toaster, kettle, etc.) as it avoids conflict. Lodger gets their own shelf in the fridge and freezer. Don't try and ban the lodger from the lounge as a PP suggested - no one wants to be made to feel unwelcome, and it's not going to store up goodwill.
It is a bit like flat-sharing BUT there's a very different power dynamic, as you essentially have the upper hand. I try to treat my lodgers as equally as possible, but there is always a power imbalance. One of the reasons for this is that they are excluded occupiers, not tenants, and have very few rights - if it's not working out you can give 'reasonable notice' (a month, normally) and end the arrangement.
To dip your toes in the water, consider having your first lodger as someone who only needs a room short term, for a month or two. It will allow you to see how you feel about it, without having to feel guilty about evicting someone if it doesn't work out, as there is a natural end date. Some people prefer to have a string of short-term lodgers as they never get their feet under the table, as it were, though the disadvantage of short-term lodgers is that they're often coming straight from their usual hometown (I even picked one up from the airport once) so you don't get to meet them beforehand.
www.spareroom.co.uk is the main site for finding a lodger; the nice thing about it is that you can browse the adverts that potential lodgers write about themselves and get an idea of what's out there.
If you do decide to advertise your spare room, my advice would be to be super upfront about everything. If that puts some people off, that's fine, those are the people you want to put off. Things like any planned building work, your cat with an attitude problem, your need for daytime quiet because you work nightshifts, your passion for yodelling... put it in. You may get lucky and find a vet nurse who works the 9-5 and has a passion for music (or is profoundly deaf...)