Before I moved DH in, I lived alone on & off for years & years - probably as much time on my own as not. It has its' good points, and it has its' iffy points. I love having peace & quiet when I get home from work, so it's heaven for me when DH is on late shifts. DH & I are both used to living on our own, so we are both quite good at eating separately if we don't fancy eating the same thing, and we do have very different culinary tastes! I'm everso slightly dreading when he retires, as he'll be under my feet the whole time 
I think that living on your own is an important part of figuring out who you are, and ultimately what you want in a relationship. You can develop your own interests and hobbies, and you don't have to compromise.
The best thing about living on your own is the control element. You can decide how your finances are going to work (if DH wasn't here, I'd abandon the television costs completely, using broadband only), you can decide the things that are important to you and focus on them - so, for instance, with your flat, you could decide whether to save up for some outrageously flamboyant paint and curtains for the living room, or you could decide to save up for that dishwasher you've been getting the envy for. Your decision.
In my case, I left a relationship a number of years ago where I compromised on a lot of things to do with colour. I moved back to my flat with not a great deal of stuff (I had to sleep on a blow up mattress loaned by my mum for a few weeks!). When funds allowed, I went nuts on the Argos website to get stuff like plates, mugs, bowls etc. They were all mad colours, even things like my iron and hoover were bright colours. The whole point was that I did it because I could!
I never really had a problem with the paperwork side of living on my own. The problem I had was more around dealing with other residents who lived in close proximity to me. I really had to develop an attitude of "what I am hearing is real, I am not just a fusspot, you need to sort your bloody noise out". That was insanely difficult - I would literally only complain about things if I had a witness to hand who could back me up as to the impact that others' actions had on my quiet enjoyment. I suspect that were I in a similar situation now, I might not be so timid.
I would not recommend getting a lodger, as they bring a whole host of other issues with them. Mine shat on my cat for a start!