@Rosalind41, I too only rent out one room with a shared bathroom, which I've been doing for nearly 3 years. My guests also have access to the kitchen, dining area and outside areas. It took some getting used to at first (having complete strangers in my home) but on the whole, it works well and I have met some wonderful, interesting people from all over the world.
Just a few tips from my perspective: I initially allowed guests to cook, but quickly realised that wasn't going to work for me because I had people cooking nearly every night, meaning I couldn't get into my own kitchen to cook (plus all the problems with burnt pots, burnt bench tops, grease spatter, rubbish, etc.). Guests still have access to kettle, toaster, microwave and fridge and are welcome to prepare light/non-cooked meals. This works SO much better for me.
Second, I used to allow guests access to my lounge/TV. But again, I realised that this wasn't going to work for me because the lounge (which doubles as my home office) is the only room in the house apart from my bedroom that I can have my own space in. My guests are welcome to lounge around the dining table and quite often I will join them there for a meal, a glass of wine or a chat. But then I have my own space to retreat to if I want.
Third, I try to make the bedroom as warm and inviting as possible so guests feel comfortable hanging out in there (rather than in my space). I'm happy to interact with my guests, but I do have people here most of the time, so it's quite full on.
If you decide to go ahead, you will work out what works for you and what doesn't. It sounds like the extra bathroom will help. I agree with Melanie that you might want to start with just one room to see how you go. I also recommend not activating Instant Book until you get used to it.
On the whole, I have found being an onsite host a very enjoyable experience. Good luck with it!