You are going too fast and need to slow down but... I would like to ask a few questions.
Did your BF say it was too early to meet your child for the childs sake or his? Both are reasonable responses but it informs the way forwards.
How do you envisage this progressing as since you have joint custody, its unlikely Dad will allow you to move abroad with his child so will new boyfriend move here, if that is possible. Is he British or will he need to apply to gain entry to be able to live with you.
You are asking a lot of him and if he is not British, then him coming here, maynot be as fruitful as you hope. This means his reticence to meet your child is fortuitous on many fronts. Neither want to get hurt and forming attachments before you know the legal viability is another reason to hang back.
If he is British and can easily return, you are still asking a lot of your new fella. Be cautious. At the moment when you meet its like you are both free and single, your child is not in the mix to affect your availability, priorities and relationship - you are in an unreal state because this is not reality.
Your bf (he is not your partner - partners share everything) sounds like he is being sensible.
But before things progress, you need to answer the above questions about who would live where, if you haven't already. I'm thinking of you here, if he won"t/can't come here then what is the point of the relationship? You could be self sabotaging.
My husband and I were a long distance relationship and we spent 3 long, intense days with each other every fortnight and the fact is that in those three days we probably devoted more time to each other than we would have over the fortnight had we lived close to each other. BUT, it wasn't reality, we were in loved up bubble mode, when the normal woes of daily life come into the mix, its then you know if the relationship is a keeper so BF is right to hold back as long as its for the right reasons and you need to roll with this.
If you are serious, when you next see bf, sit down discuss realistic expectations about what needs to happen for him to meet
your child, this could be the passing of a set amount of time, agreement about who would live where or just confirmation that this relationship with you three as a family is actually something you both envisage happening in the distant future...if not, walk away.
It worked for me, it can work for you but you need to step outside the love bubble as your child comes first. Think with your head, address all issues and expectations and be realistic.
I wish you the love and happiness I have x