Thank you all for taking the time to leave your comments - not all of which I'm in agreement with 
Lots of assumed arms are being granted, and I don't really see anything presumptuous in wanting to mark my family on the heraldry map. I am going into this quite seriously (but hoping it will be a pleasurable experience ......) and from what I see, I think everyone is entitled to bear arms - in some cases, differenced where family arms already exist, but, as you say, usually subject to registration of some kind. [...]
I've designed my own coat of arms, following the rules of heraldry (because I'm interested in it) and ensuring to the best of my ability that there are no other arms that clash with it, purely because I think it's bad manners, actually, just to rip off someone elses arms. I don't claim antiquity for these arms, or that they've been granted by any particular that in fact hasn't. If either male OR female descendents of mine want to use them, I again can't see a problem with that.
I genuinely don't see the problem, especially where England & Wales is concerned (Scotland's a little different, legally). The reason why the Royal College of Arms was set up in the 15th century, in my view - apart from sorting out unrelated people adopting the same arms - it was an attempt preserve a privilege that the elites of the time felt was being diminished, as by then it wasn't just the upper classes that were adopting arms but anyone who was anyone, merchants, etc. Previous to that, people did simply arms arms as part of the paraphenalia of chivalry, which is all that it was: a sort of logo, an adornment.
Likewise, a lot of arms do have family history attached them, and symbolism: but plenty in fact don't, or it's been long since forgotten. I think we can record history by means other than a few colours and symbols, anyway.
The records of the Royal College of Arms themselves are not complete, because their visitations (1480s-1640s, something like that) failed to record all arms of every parish. Part of the reason why they were objected to was precisely because this or that person didn't want their lowly family origins and lack of "entitlement" to arms revealed. Moreover, the existence of the College did not prevent people from assuming arms, which was just as widespread (notable of recent times was the
family arms of Sophie Rhys Jones as she then was).
Assuming arms in England & Wales is technically illegal (or displaying someone else's as your own) - but it's a chivalric offence, and the court to try such offences ceased to exist in the 1730s, in part because it was hammering people who it was claimed to have no right to arms but relying on the incomplete records of the Royal College to do so, since visitations had been abandoned and it wasn't definitively known who was or was not entitled to arms.
There was one case in 1954 (I think it was) when an enthusiastic legal-minded King of Arms did re-convene the court to see if the machinery worked (a theatre was using Manchester City's coat of arms without permission) but part of the judgement was precisely that the court would be unlikely ever to reconvene (although it did find in favour of the council), and a further king of arms in the 80s ruled out the possibility. My understanding is that because of changes to the legal system since, it would be impossible to reconvene, anyway. (In Scotland, the Court of the Lord Lyon has a different legal status).
So if you can't enforce a right, you don't have it. On that basis, paying several thousand pounds - as increasingly local authorities and universities do - to the College is an utter waste of money, although I'm sure the vellum looks nice on the wall, and in reality makes it no more "official" than assumed arms. It's just a game, like the whole ridiculous feudal legacy of titles. (No one can stop you from adopting a title, such as the Duke of so-and-so, as long as it's not one that's being used, because you'll risk impersonating a real person.)
The web site of one Parish Council of which I'm aware threatens legal action against anyone who uses their coat of arms, demonstrating a lack of understanding of what they've spent (wasted?) taxpayers money on and their petty-mindedness to actually include such a threat. I'm tempted to call their bluff on it, in fact, and temporarily adopt their arms.
In fact, given the history of arms, I'd go so far as to say that assuming arms has a longer and more established tradition than the "official" method and is in my view certainly more democratic (and cheaper!):
Liberté, Egalité et Fraternité indeed.
100% with you, Brenda.