Hi Lucy,
Generally they say bleeding plus no cramps not worrying,
bleeding plus cramps can be a little more worrying as a symptom.
Have you got a pregnancy test handy?
I'd be tempted to use it, if you get a BFP then go to the nearest EPU (emergency pregnancy unit, most hospitals have one, you can google) and ask if they can do 48 hour bloods for you.
4+4 is too early to see anything on a scan, so they way they can check is to take your blood, measure the amount of HCG and then take it again in 48 hours time. In a successful pregnancy it should double every 48 hours, if it doesn't rise much, it indicates things aren't good. It is a way of being sure what is going on.
The other option is to wait and see i.e. see if the bleeding continues to get heavier, test every morning to see if you are still getting positive tests etc but I have found this does lead to quite a long wait sometimes, so I'd prefer to know with a test if possible. Some people would rather wait it out than have to go to the EPU, it is a personal thing.
If it is a successful PG, then the bleeding and cramping should stop. If it is an early MC then it won't. When I've had one at under 5 weeks, I have found it like a heavy period, unpleasant, but not too bad physically to cope with, just very distressing emotionally.
I'm going out now but will check in later to see how you are doing. x