Considering moving in with my boyfriend?

I think you ought to get your own place. I've got no problem with people living together. However, young women who move from their parent's home to their boyfriend's home are robbing themselves of the chance to define themselves without an authority figure putting their stamp on them first.

Seriously. Get your own place, have roommates if you need them.. but listen to your own music, your own thoughts, your own opinions, read your own books, keep your own hours, develop your own interests, pay your own bills, work your own job. You can date your boyfriend during all this but you WILL GIVE UP a great deal of your individual development if you move in with him BEFORE simply moving in with yourself.

most couples don;t have ups and downs while dating

Hello, ?!

Bear in mind that sharing a flat is a lot different than being able to leave it for whatever reason and return home. I put it thusly because that is the first thing I became aware of when I moved into my ex-wife's apartment years ago from my parents' apartment, the loss of that freedom. You are, of course, old enough to make that decision on your own without your parents' approbation but do take the time to think about it. Moving in with your boyfriend may save you money in one respect but you will then be expected to share with the household expenses and food, which can add up to the extent where it will seem as if you aren't saving money at all. The biggest aspect to moving in with him will be, of course, the loss of autonomy, the kind of thing that you've taken for granted for much of your adult life but will have to compromise quite a bit of it in order to etch out your living space with him. Mind you, if and when you have a disagreement, which is bound to happen, there will be no walking away from it and seeking solace in your own space; his space will become in effect your space and whatever contretemps that arise will have to be worked out within a constricted space; this takes a while to get used to. Remember, your mum and dad allowed you freedom of movement as long as you respected the sanctity of their home; you are their child. However, your relationship with you boyfriend is still "wet behind the ears"--a seven-month's-long relationship has barely gotten off the ground--and you know precious little about the man on a mundane, day-to-day basis when sex is not high on the menu and boredom begins to enter the bedroom. Keep all this in mind as you prepare to say goodbye to all those childhood memories at home and embark on a new life with the man you love. It can be an adventure or it can be a disaster; either way, it's not the sort of thing you enter upon willy-nilly. For many people, it's the first real sign of adulthood.

(p.s., I have had the pleasure of responding to your post from New York City on a pleasantly warm Tuesday afternoon. I like to mention this to "askers" who post from the UK.)

p.p.s. I read your addendum and wish to say this: Unless you have promised your parents that you will in effect be their caretaker (I have been there, too, as my father was also in poor health while I was at home with them) you are still free to make the decision to move. If you are in doubt, try not to use your parents as an excuse to delay moving in with your boyfriend. You're going to experience doubts because a decision of this will invariably change your life so now is the time to grapple with and resolve them to your satisfaction. You don't have to spend every minute of the day with your parents in order to enjoy quality time with them nor should you feel obligated to remain at home but it will be important for you to set aside time with them and make sure that you're consistent because your parents will come to depend on it. Remember what I said about compromise? You will have to etch out meaningful time with your boyfriend while also taking care not to sacrifice the time you seek to maintain with your parents. It's not an easy juggle. Don't burden yourself with the prospect of being selfish; whatever decision you make regarding your living situation, take responsibility for it. Give your parents the benefit of the doubt in realizing that their daughter is a grownup and that they will love you no matter what you decide to do.

ADDED: I also forgot to mention well it's hard to explain, it's like I don't want to move away from my mum & dad because they might not be here for much longer, that every second counts and That I am worried that I don't spend enough time with them. Although I need to move on with my own life I don't want to be selfish and leave my mum and dad. My dad isn't very well and I don't want to dump and the stress into my mum

If you are scared at 20 years old, then no, you shouldn't. At 20 you should be excited about exploring all the opportunities life has to offer, not wanting to continue sucking at the parental teat.