I had my dating scan at 6+4 (external with 1 litre of water 1 hour before the appointment) and we saw a little jellybean shaped bub plus the flicker (heartbeat) :-)
Having my 12w scan on Saturday (I'll be 12+5) Another external one and have to drink the 1 litre of water again...it can be a bit uncomfortable with such a full bladder!!
Congratulations! And all the best with your pregnancy :-)